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LIBRARY OF CONGRESS. 

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UNITED STATES OF AMERICA. 



ECCE CCELUM; 



OR, 



Parish Astronomy, 



Jfrt Si* H^uiuxtB. 



BY A CONNECTICUT PASTOR. 

"B Win, , ^v^rJiv J 1 l£c 



SEVENTH EDITION. 




BOSTON: 

NICHOLS & NO YES, 117 WASHINGTON STREET. 

1870. 



Entered, according to Act of Congress, in the year 1867, by 

NICHOLS & NOYES, 

In the Clerk's Office of the District Court of the District of Massachusetta 



/■' 



boston: cornhill press. 

STEREOTYPED AND PRINTED BT GEO. C. RAND & AVERT. 



Co 



Rev. W. A. Stearns, D.D., LL.D., 

President of Amherst College, 
TfcCDS VOLUIRllI 

OF PARISH LECTURES ON ASTRONOMY IN THE INTEREST 
OF RELIGION, 

IS RESPECTFULLY DEDICATED 



BY 

THE AUTHOR. 



A REMARKABLE BOOK. 



ECCE CCELUM; 

OR, 

PARISH ASTRONOMY. 

By Rev. E. F. BURR, D.D. 

1 vol. 16mo, 198 pp. Price, $1.25. New Edition. Sent prepaid by mail 
on receipt of price. 



NICHOLS AND NOYES, 

117 Washington Street, Boston. 



The Publishers request special attention to the following un- 
solicited testimonials, which hare been received from sources 
worthy of regard. 

From Rev. W. A. Stearns, D.D , LL.D., President of Amherst College. 
" I have read it with great profit and admiration. It is a grand 
production, — very clear and satisfactory, scientifically considered ; 
very exalted and exalting in spirit and manner ; and exhibiting a 
wealth of appropriate emotion and expression which surprises me. 
May the life and health of the author be spared to show still 
further that God is and that His works are great, sought out of 
them that have pleasure therein." 

From Rev. Horace Bushnell, D.D. 
" I have not been so much fascinated by any book for a long 
time, — never by a book on that particular subject. It is popu- 
larised in the form, yet not evaporated in the substance, — it 
tingles with life all through, — and the wonder is, that, casting off 
so much of the paraphernalia of science, and descending, for the 
most part, to common language, it brings out, not so much, but so 
nuch more of the meaning. I have gotten a better idea of Astron- 



omy, as a whole, from it than I ever got before from all other 
sources, — more than from Enfield's great book, which I once care- 
fully worked out, eclipses and all. 

" I trace the progress made, and the methods of the same, and 
seize on the exact status of things at the point now reached." 

From the Bibliotheca Sacra. 
"This is a remarkable book, — one of the most remarkable 
which has proceeded from the American press for a long time. It 
lifts the reader fairly into the heavens and unveils their glories. 
The presentation is very full though concentrated, very clear and 
animating, — with a command of language and a glow of eloquence 
which is quite extraordinary. The last lecture is hardly less than 
a Te Deum. The only adverse criticism which, on reading the 
preparatory lecture, we were inclined to make, was, that the almost 
impassioned eloquence with which it opened would have bean 
more impressive further on, and after the imagination had been 
excited by the facts. But, after finishing the last Lecture, we 
could not wonder that a mind so full of the great facts, and of the 
emotion which they necessarily kindle, should, on seeing his own 
parish charge assembled to listen, break forth in strains which* none 
but a mind fully roused by his theme and his audience would 
have been able to utter. No person can read through this volume 
without mental exaltation, and a conviction of the peculiar ability 
of the author." 

From the New Englander. 
" It presents an admirable re'sume of the sublime teachings of 
Astronomy, as related to natural religion, — a series of brilliant 
pen-photographs of the Wonders of the Heavens, as part of God's 
glorious handiwork. The first five lectures pass the science in 
rapid review ; the last treats of tlie Author of Nature, as related to 
its leading features. There is not a dry page in the volume, but 
much originality and vigor of style, and often the highes* elo- 
quence. It is, withal, evidently by an author at home in his sub- 
ject, not " crammed " for the task. It affords a fine example of 
what an intelligent pastor can do, outside of his pulpit, towards 
training an intelligent people, and by imparting to them Nature's 



teachings, leading "through Nature up to Nature's God," — the 
God of Revelation as well. To such a book the author need not 
hesitate to affix his name." 

From Rev. A. P. Peabody, D.D., LL.D., Preacher to Harvard University, 
and Plummer Professor of Christian Morals. 

" Permit me to thank you for a work in which you have effected 
a rare union of scientific accuracy, eloquent diction, and rich de- 
votional sentiment. It is attractive, instructive, and edifying. It 
appears at a time when science needs, as never before, to be 
redeeme 1 and sanctified by faith in Him, in whom are hidden all 
the treasures of wisdom and knowledge. And, best of all, it does 
not make Religion cringe to Science, but maintains her in that 
queenly status which is the only position she can hold. The book 
must do great good, and I heartily congratulate you as its author." 

From Rev. S. H. Hall, D.D. 
"Ecce Coelum is much more than a book-success. It will be 
honored as a most timely and admirable treatise to put into the 
hand of thoughtful young people, to ' turn off their minds from 
vanity,' and lead them to God." 

From the New- York Evangelist. 
" This unpretending, though elegant little volume, gives a most 
admirable popular summary of the results of Astronomical Sci- 
ence. The author has evidently mastered his subject, and he has 
presented it in a most striking manner, adapted to the comprehen- 
sion of the common reader, and enriched with pertinent illus- 
trations. The book is perhaps the most fascinating treatise on the 
science which has been published of late years, ranking indeed 
in many respects with that of the late lamented and eloquent 
Mitchell. One of its excellencies is that it does not hide God 
'behind his own creation."' 

From the Religious Herald. 
" A New Book, and one that is a book, worth its weight in 
gold or diamonds, for it is full of gold and precious gems, — dia- 
monds of law and fact, — truths beaming with celestial light. J 



ipeak of ' Ecce Ccelum,' from the pen of Eev. Enoch P. Bukr, 
D.D., of Lyme, Conn., published by Nichols & Noyes, Boston, a 
duodecimo of 198 pages. Mr. Burr modestly signs himself 'A 
Connecticut Pastor,' but some college has rent the vail and written 
out his full name, and added to it a D.D. So much the better for 
Connecticut and for the world. Such light as the book contains 
ought not to be under a bushel. 

'* These six Parish Lectures are a masterly, vivid, easy, sub- 
lime presentation of the enchanting facts of Astronomy. They 
are adapted to all classes, — the learned and the unlearned. The 
astounding glories of the skies are tempered to our humble eyes. 

" Let all read the book, old and young. Let it be found in 
every school, in every library, and .in every home where wisdom 
is invoked. Read it, and you will exclaim, what glorious light it 
sheds from the throne of God upon the lonely pathway of man ! " 

From C. H. Balsbaugh, of Pennsylvania. 
" It is certainly a wonderful little book. How the world 
shrinks into an atom as we follow the lofty soarings of the ' Con- 
necticut Pastor.' I never knew rightly what Dr. Young means 
by saying, ' an undevout Astronomer is mad ; ' but I now see and 
feel the power and beauty of the expression. Such a book cannot 
be read without laying upon us the responsibility of a new charge 
from heaven. After contemplating such grandeur, we instinctively 
exclaim, ' What is man that Thou art mindful of him 1 ' " 

From Hon. S. L. Selden, Late Chief Justice of New York. 
" A beautiful book. I admire it for the elegance of its style, as 
well as for the lucid and able manner in which it presents the 
noblest of the sciences. It will prove, I think, very valuable, not 
merely for the knowledge it communicates, but as suggestive of a 
line of noble and elevated thought. And I am much pleased to see 
from the numerous notices which have come under my observa- 
tion that my estimate is confirmed by many persons of the first 
capacity for judging. To have written a work which receives 
and deserves such very high praise from scholars and men of 
science cannot but be a source of great gratification to the 
author." 



CONTENTS. 



I. Preparatory. 

i USES 9 

t. HISTORY 16 

3. INSTRUMENTS OF INVESTIGATION . . . . ao 

II. The Sky. 

1. ASPECT 33 

2. NATURE 39 

3. NATURE OF CONTENTS _ . .43 

4. ARRANGEMENT OF CONTENTS 49 

III. Satellite Systems. 

Example — Earth and Moon. 

1. DIURNAL REVOLUTIONS 66 

2. MUTUAL DISTANCE 70 

3 SHAPES AND SIZES 71 

4. MUTUAL GRAVITATIONS 77 

5. MASSES AND DENSITIES 81 

6. ORBITS 84 

7. MUTUAL ASPECTS 87 

5 



b CONTENTS. 

IV. Planet Systems. 

Example — Solar System. 

x. ORDER OF BODIES 93 

2. PERIODS 103 

3. DISTANCES FROM SUN 105 

4. SHAPES AND INCLINATIONS OF ORBITS . . . 1x1 

5. SIZES iiS 

6. VELOCITIES 117 

7. MASSES AND DENSITIES 118 

8. PERTURBATIONS 120 

V. Higher Systems. 

1. SUN SYSTEMS 125 

a. GROUP SYSTEMS 137 

3. CLUSTER SYSTEMS 138 

4. NEBULA SYSTEMS 140 

5. ULTERIOR SYSTEMS 146 

6. ULTIMATE SYSTEM 148 

VI. Author of Nature, 

As Related to its Leading Features. 



1. VASTNESS 








159 


2. VARIETY IN UNITY 








163 


3. FINISH OF MINIMA 








168 


4. WISDOM 








171 


5. DYNAMICS 








177 


6. RELATION TO LAW 








182 


7. RELATION TO TIME AND MOTION 








188 


8. MYSTERY 








193 



L 
PREPARATORY. 



I. Preparatory. 

i. USES 9 

2. HISTORY if 

3 INSTRUMENTS OF INVESTIGATION . JO 



FIRST LECTURE. 



PREPARATORY. 

ASTRONOMY, the science of the stars, does 
not limit itself to those bright points in the 
vault of evening which are commonly called 
stars, but treats of the Sky with its whole star- 
like belongings — Sun, Moon, Planets, Comets — 
whatever of this general nature reveals itself in 
the entire round Heavens. 

What is the use of Astronomy ? Had this 
question been asked a few centuries ago, most 
intelligent persons would have said that its 
chief use was to aid astrology. Somehow, men 
had conceived the idea that the fortunes of 
individuals and nations were bound up with the 
aspects and places of the heavenly bodies, and 
could be predicted from them. It was univer- 
sally believed that, could the places of certain 
bodies in the sky at the birth of any person be 
well ascertained, it would be possible to infer the 
general character of his lot in life and its criti- 
cal periods. Here was grand motive for study. 

9 



10 FIRST LECTURE. 

Men have always had great taste for being pro- 
phets and hearing prophets ; so, with infinite zeal 
and pains, they watched the mazy heavens, and, 
out of such glittering fractions of information 
as they could gather, built up, as their chief 
use, a stupendous system of fortune-telling whose 
Twelve Houses, whose Lords of the Ascendant, 
whose Horoscopes and Nativities, were the busi- 
ness of sages, and the trust of monarchs and the 
people for thousands of years. 

It is well that we have some better reason 
than its astrological uses to give for studying the 
Science of the Sky. 

See where the sun, with face of insufferable 
splendor, goes swimming through the day ; see 
where the soft and silver moon, with fleets of stars, 
goes swimming through the night ! What an 
eloquent silence ! There they shine and move, 
perhaps wonderfully achieve — hosts upon hosts; 
but there is no celebrating pomp of sounds, 
only an all-embracing pomp of silence — not a 
whisper, not a rustle, through all the vasty dome. 
Our dinned ears and hearts are soothed. Our 
petty cares and excitements are hushed. Both 
body and soul are insensibly calmed and refreshed 
as we gaze into the immeasurable stillness. 

Was ever so noble a sight ! What kindly in- 
terweavings of the great and the lovely — what gor- 
geous competitions and combinations of the majes- 
tic and the beautiful — and all steeped in the 



USE OF ASTR0X03IY. H 

grave gbry of immemorial and supreme antiquity. 
The skj does not look old. Other books show sad 
marks of the passing years. Their pure white sul- 
lies. Their varnished, sharp-cut characters grow 
dull and vague. Scars and. molds and odors of de- 
cay gather upon them. Not so with this pageant 
book opened above us, this illuminated missal of 
the heavens. It shows a page as delicately fair 
and fresh as if it had just come from the hands 
of its Author. And yet it is the world's ancient- 
est heir-loom, the issue of the eldest dawn : and, 
as we look upon its broad and pictured page, 
we are reverently aware that the same shining 
scripture met the gaze of famous empires long 
since dead and buried ; of those old men of renown 
whose forms loom gigantically on the outskirts 
of tradition ; of him, hoarest ancient of all, the 
Old-Testament Adam. It is a joy and an exalta- 
tion to peruse such a Natural Bible. 

And then it is so accessible ! Not, like some 
rare old volume of price, hid away from the 
people at large in piles of granite architecture ; 
railed off heavily from the curious handling and 
close inspection of most of such as are allowed 
to roam the stately halls ; permitted to unclasp 
only under the careful hands and cultured eyes 
of sages and princes — not such is this azure 
volume above, printed and pictured in silver and 
gold. It is a book for the people. Its outspread 
page invites study from all quarters, by day and 



12 FI2ST LIJZTP.Z. 

by night. One can : eyes on it as freely 

another. If it has any valuable any 

precious wisdoms in it, one is just as welcome as 
another to do what he can toward finding them. 
God permits no censorship. Bis printing is a true 
publishing. With both hands he has issued his 
:>nomy ; has put it in characters large and 
shining enough to be within the range of all ey 
has opened it as wide as wide can be, and laid 
it across the sky's fair face for all who choose to 
mine, stand they at palace-g :id they 

at cabin-doors, stand they in the silent domes of 
sky-piercing observatories, stand they on the rat- 
tling mid-road of affairs. All classes welcome 
— welcome to that divine calm, to that refined 
and exalting pleasure, to that jubilee of sight 
and poetry and art, to that feast of the gc 

And not only to this sensuous and aesthetic 
banquet which lies spread on the golden surface 
of things for all who have eyes and souls, but 
to the more interior and recondite stores of which 
these others are mere tokens and crumbs. For 
the sky is not only an accessible book, but, in 
these last days, an interpreted one. It has been 
translated out of its aboriginal hieroglyphics, put 
into the world's vernacular, done into alphabet 
even, as to its most essential facts. The inter- 
pretation was hard. Sometimes it seemed as if it 
would never be made. It actually took great 
men, and many of them, to make it ; and many a 



USE OF ASTRONOMY 13 

long age crept away while the work was being 
done. But, lo ! done it is at last ; and the re- 
sults, though not the methods, are now level with 
the commonest men. And they are exceedingly 
serviceable results. Once, men could not see an 
eclipse or a star with a tail to it without infer- 
ring pestilence and war ; could not even see a 
bloody sun or shooting star without fearing na- 
tional disaster and the fall of thrones. But now 
humanity no longer falls a-trembling at the signs 
of heaven. The progress of astronomical science 
has freed us from our superstitious terrors. We 
leave such panics to centuries ago and the hea- 
then. Thanks to the sages who have interpreted 
to us the Sibyls of the sky ! Thanks to them, too, 
that commerce no longer rows her scant and 
Liliput shipping in timid adventure within her 
native creeks, and along her native shores. To 
the science of the stars we owe the safety and au- 
dacity with which unlimited canvas now stretches 
across the widest seas and darkest nights. By 
the improvements it has been the means of in- 
troducing into mathematics and observation, it 
has raised the whole body of our art and sci- 
ence ; in fact, created large portions of each. 
Scarcely a branch of business or knowledge, how- 
ever humble, or however high, but is debtor, in 
one way or another, to astronomical investiga- 
tions. Astronomers first taught men the art of 
questioning Nature. They were the first inter- 



14 FIRST LECTURE. 

preters of her that deserved the name, the first 
to give dazzling and triumphant examples of the 
way o c extorting secrets from her close-fisted 
keeping. In education, also, astronomy has heen 
of most material service. A large and generous 
culture of the mind requires familiarity with a 
wide variety of ideas. "We need to be trained to 
refined distinctions, to subtle analyses, to acute- 
ness of thought ; and for this purpose other sci- 
ences will answer better than astronomy. But 
we also need, still more, culture in breadth and 
dignity and gravity of ideas, in comprehension 
and solidity of understanding, in elevation and 
durable glow of imagination and character ; and, 
for this purpose, no branch of secular knowledge 
can compare with the science of the stars. This 
science is worth more than all the fictions and 
poems in the world as a judicious cultivator of 
the imagination and corrector of insipidity and 
tameness of character. It is universally admit- 
ted to be the sublimest of the natural sciences. 
It is a poem as well as a science — the best ex- 
ample we have of polished completeness in a 
science, and the noblest specimen we have of an 
epic poem. Not Milton, not Homer, ever sang 
so sweetly and loftily as do the chief theorems of 
astronomy. And certainly, if one would get just 
ideas of the grandeur and possibilities of the hu- 
man mind, in no way could he better accomplish 
his purpose than by noticing what great astro- 



USE OF ASTRONOMY. 15 

nomical problems that mind has grappled with 
and conquered. It has been the war of Jupiter 
with the Giants. When we look at the mighty 
secrets that men have wrested out of that starry 
page above us, we say softly and reverentially 
to ourselves, "In the image of God made he 
them. ,, We also feel that what man has done 
man can do. We are encouraged for the future of 
science, the future of art, the future of every thing 
requiring great endowments in man. But, after 
all, the most interesting and useful thing about 
astronomy is the illustration it pours on the attri- 
butes and glory of the Supreme Being. Let it be 
repeated, that ancient sentiment, " An undevout 
astronomer is mad." If one can thoughtfully 
pace up and down the star-sown fields of astrono- 
omy and not conceive a feeling of religious awe, 
as in the presence of Incomprehensible Almighti- 
ness, he must be a rare man, a sinner above all the 
Galileans. The fullest force of this inspired say- 
ing, " for the invisible things of Him are clearly 
seen, being understood by the things that are 
made, even his eternal power and godhead," — I 
say, the fullest force of these words is only felt 
by him whose thoughts, leaving the diminutive 
objects of this world, have gone voyaging through 
the inexhaustible wonders of the firmament and 
gazed intelligently on the files of that infinite ar- 
mada of luminaries, which, in exquisite harmony 
and solemn pomp, cruise up and down yonder 
shoreless ocean of the heavens. 



16 FIRST LECTURE. 

Astronomy is universally admitted to be the 
most ancient of all the natural sciences. How 
ancient none can tell. Neither history nor tra- 
dition carries us back to its beginning. We can 
learn nothing of its founder or founders. Their 
very names are lost in the darkness of the primal 
ages. At the time when we get our first clear 
view of the science, viz. two or three thousand 
years before Christ, it had already made very con- 
siderable progress. Some say that Chaldea, with 
its beautiful atmosphere, was the native country 
of astronomy ; others stand up stoutly for Egypt, 
"mother of sciences"; while still others think 
favorably of the claims of India, with its most 
ancient of all astronomical tables, the tables of 
Tirvalore, and its most ancient and studious Brah- 
mins. Who know ? Not even those persons who 
have taught that the cradle stood in this country 
by claiming that here stood the cradle of the hu- 
man race — that fossils of the human period in the 
United States go back to a remoter antiquity than 
those in any other part of the globe ! Astronomy 
was cultivated in very remote times — hundreds 
and perhaps thousands of years before the Chris- 
tian era — by the Chinese as well as by the East- 
Indians, Egyptians, and Chaldeans. Since the 
time of reliable history, however, the science 
has been in a state of decay, if not extinction, 
among most of these nations. With some it 
has long been one of the totally lost sciences. 



HISTORY OF ASTRONOMY. 17 

We look in vain for a living astronomy through 
all the countries of the East. We find nothing 
but a fossil, and a mutilated fossil at that. Civil 
troubles, with other causes perhaps, killed and 
buried it before the historic period in all those 
remoter Oriental lands. In Egypt, however, and 
subordinately in Greece, the science continued 
to live and occasionally grow till within times 
quite modern. The world will not willingly let 
die such names as Thales, Pythagoras, Hippar- 
chus, Ptolemy ; nor the glory of that famous 
Alexandrian school, which, from three hundred 
years before Christ, till the sack of Alexandria 
and the destruction of its famous library, in the 
seventh century, continued to toil away, and not 
without success, on the heavens. That terrible 
vandalism that destroyed the garnered wisdom 
of so many centuries suppressed astronomical 
culture in the West for nearly a thousand years. 
The old Romans were fighters, never astrono- 
mers. Their disjecta membra, the middle ages, 
were fighters, never astronomers. Meanwhile 
the cast-away science found a home among the 
Arabs. At Bagdad, under the caliphates of the 
Abassides, arose a new Augustan age for all sorts 
of learning. Equally enlightened and powerful, 
those splendid monarchs gathered about them- 
selves the cultivators of knowledge from every 
quarter, and spared neither pains nor gold to 
make their capital the focus of the world. And 



18 FIRST LECTURE. 

they succeeded. While it was unrelieved mid- 
night in Europe, it was midnight lit up by cal- 
cium lights in Arabia. Immense attention, in 
particular, was given to astronomy ; and the 
mere names of those Saracenic philosophers who 
cultivated this and other branches of liberal 
knowledge would fill a volume. Moreover, it 
was from the splendid and enlightened king- 
dom which the Arabs established in Spain that 
astronomy was again set on her feet in the rest 
of Europe, at the beginning of the sixteenth 
century, after well nigh a millennium of exile. 
After all, the amount of real discovery in the heav- 
ens made, up to this time, by all these illustri- 
ous men and schools, of various nations, for thou- 
sands of years, was comparatively small. Many 
a single year since has done more for astronomy 
than was done by all the many thousands of years 
before. The fact is, the old astronomers were de- 
stroyed by their theories and visionary philoso- 
phies. Instead of carefully observing Nature and 
drawing their systems from it, most of them first 
arbitrarily formed their systems and then en- 
deavored to interpret Nature in consistency with 
them. Like many people now, they scorned to 
begin at the beginning. They wanted to build 
their house from the roof downward, instead of 
building it from the foundation upward ; wanted 
to start with Euclid and Homer and figure their 
way back to a knowledge of the alphabet ; wanted 



HISTORY OF ASTRONOMY. 19 

to start with the broadest generalizations of sci- 
ence and so descend on particulars, like Plato, 
their great master or representative. In conse- 
quence very little was accomplished, considering 
the prodigious time and labor expended. It was 
not till Prussian Copernicus and his immediate 
successors cast off the old theories and way of 
studying Nature, that astronomy can be said to 
have fairly begun her triumphant career. The in- 
cubus once lifted, she then, under the lead of such 
men as Tycho Brahe, Kepler, Galileo, Newton, 
went forward with gigantic strides. Up to the 
present time, it has been one incessant tramp and 
thunder of discoveries. Scarcely would one great 
truth flash down from the sky before men's at- 
tention would be called to another. Much of the 
time, indeed, these truths have come in showers 
and set the whole sky ablaze. It is not much ex- 
aggeration to say that the heavens, instead of 
raining stars upon us once every November, are 
raining them nearly the whole time. Like the 
tributaries of some Mississippi or Amazon, con- 
tributions have flowed into the main astronomical 
current from every quarter and Christian land. 
The French (a wonderful nation for every thing 
save religion and self-government) have particu- 
larly distinguished themselves. Since Newton, no 
names in science so glorious with achievement, 
to none will a grateful posterity so freely decree 
triumphs, as to those of Clairaut, La Grange, 



20 FIRST LECTURE. 

La Place, and Arago. The English-speaking 
race have also found laurels growing in the sky 
and have liberally plucked them — witness Flam- 
stead and Halley and Bradley and Maskelyne and 
the two Herschels. For Germany and Russia, 
are the great names of Bessel and Argelander and 
Struve and Maedler — names inseparably con- 
nected with some of the most recent and dazzling 
successes of astronomy. They have added, not 
cities, but provinces, to her empire. Altogether, 
the astronomers of the last three hundred years 
have given us the most extensive, sublime, and 
complete science to be found in the world. 

And by what means were these grand results 
reached ? The naked eye has done something — 
done much. In remote times, men had nothing 
else with which to explore the heavens : but this, 
with the help of the pure Chaldean air and leis- 
urely shepherd life ; this, with the help of the 
perpetually cloudless Egyptian sky and the free, 
secluded life of the cultured and inquisitive 
priesthood, was sufficient to lay the foundations 
of astronomy. Even to this day, the unaided 
eye has made, and it need not despair of still 
making, discoveries in the heavens. Next, as- 
tronomy is indebted to artificial instruments — to 
telescopes, and instruments for measuring angles. 
Contrivances for measuring the angular distances 
of the heavenly bodies from each other were first 
used about three hundred years before Christ, at 



INSTRUMENTS 01 INVESTIGATION. 21 

Alexandria. They were very rude ; so much so, 
that Hipparchus and Ptolemy considered it a great 
achievement to measure angles of 10' — about one- 
third of the moon's diameter as it appears to the 
eye. But even such rude approximations to the 
places of the stars accomplished several discover- 
ies, and gave the charts and catalogues which 
have contributed to still more and greater dis- 
coveries in modern times. Tycho Brahe made 
great improvements on the instruments of pre- 
ceding astronomers. He found himself able to 
measure angles of 10" — an accuracy sixty times 
greater than Hipparchus could command. Hence 
another instalment of discoveries. At the present 
time we have goniometers of wonderful beauty 
and exactness — almost an equal feast to the eye 
of the poet and to that of the mathematician — 
enabling us, by management, to reach an accuracy 
ten thousand times greater than was obtained by 
Tycho with his improved instruments three hun- 
dred years ago ; enabling us to measure celestial 
arcs no larger than a thousandth part of a second. 
It is this last style of accuracy that has, within a 
few years, enabled us to find the distances from us 
and from each other of some of the fixed stars, so 
called, as well as other results scarcely less won- 
derful. But these exact instruments and their 
splendid contributions to astronomy, are largely 
due to two other means of discovery, viz obser- 
vatories and optical glasses. To secure firm sup- 



22 FIRST LECTURE. 

port for instruments, to lift them above the vapors 
that mor* or less always lie along the surface of 
the grouid and give to them a large and unob 
structed horizon, massive and lofty towers have 
been built. On such a tower — Uraniberg, he 
called it — Tycho placed his instruments and 
made his discoveries. On such towers, num- 
bered by hundreds and fitted up like palaces for 
every sort of celestial observation, a thousand 
astronomers now watch out the night all over 
Christendom — at Paris, at Greenwich, at Pul- 
kova, at Washington. Observatories are the ful- 
crums of astronomy. They are the war-towers 
from which we can best attack the skies. If the 
Tower of Babel had only been designed for such 
use, as certain incautious persons have suggested, 
there would have been much good sense in it ! 

At Florence, in the Grand-Ducal palace, there 
is a room called the Temple. The walls are in- 
laid with marble and jasper. The ceiling glows 
with superb frescoes. In niches about the apart- 
ment are disposed numerous marble busts — por- 
traits — in the best style of recent art. At the 
center, the gem and significance of the whole, 
stands a life-size statue — also a portrait — in 
whose snowy marble features one recognizes, not 
only the majesty of art, but also the majesty of a 
well-known sage whose single name is sufficient 
riches for a country. Here, in 1840, met the 
Italian men of science to ded : ^ate the proudest 



INSTRUMENTS OF INVESTIGATION. 23 

cabinet of the Medici to the great memory of 
Galileo Galilei, whose statue that is, whose dis- 
ciples' busts those are, whose leading life-events 
that glowing ceiling commemorates — Galileo, the 
first telescopic explorer of the heavens. Well did 
he deserve the honor. His single renown more 
honors his native city than do all her grand dukes, 
than would permanent rank as capital of Italy. 
And here, in a press by the wall, is the very tele- 
scope with which he made his discoveries — two 
curved glasses rudely fastened in a rude tube, 
all made with his own hands. With this simple 
instrument he created a new era in astronomy. 
With it he poured on the age such a succession 
of wonders that foolish Rome feared that the im- 
movable foundations of Holy Scripture would all 
be swept away by the deluge of innovations. As 
if her interpretations of the Bible were the Bible 
itself ! Since then, the telescope has been bravely 
plucking laurels from the sky almost incessantly. 
Made reflecting ; made achromatic ; enlarged from 
an object-glass of two inches to one of eighteen, 
and from a speculum of six inches to one of six 
feet; equatorially mounted, with all the appli- 
ances for easy motion, exact adjustment, and ex- 
tremest nicety of measurement ; planted in pa- 
latial observatories where all the heavens look in 
at the revolving dome and where scarcely a tre- 
mor of storms can find its way through the solid 
misonry ; supported on either hand by Photo- 



24 FIEST LECTURE. 

graphy and Telegraphy — in short, the Gneat Re 
fractor of Pulkova or the Great Reflector of- the 
Earl of Rosse — the telescope of late years is- still 
pushing incessant conquests in every direction 
through the sky. Formerly, the telescope was 
one ; now it is e pluribus unum ; and from thou- 
sands of Uranibergs, public and private, the won- 
der-working tube is nightly run out against the 
sky, till the civilized world fairly bristles like 
a battery in time of active war; and competing 
observers, under the spur of a generous emula- 
tion, almost nightly bring down upon the earth 
some mighty truth, or the promise of one, by 
their voiceless celestial artillery. 

Not long after the invention of the telescope, 
the means of astronomical investigation received 
another accession of at least quite as great impor- 
tance. I refer to that branch of the mathematics 
called by Newton, one of its inventors, Fluxions, 
but now universally known among scientific men 
under the name of the Differential and Integral 
Calculus. It is a species of higher algebra ; and 
its peculiarity consists in considering all finite 
quantities as expressible by the ratio of two in- 
finitely small quantities to each other. It is 
found that this mode of considering quantities 
has in it a mysterious and subtle energy for the 
resolution of problems of the higher order, be- 
yond any thing known. It is a natural magic. It 
is the quintessence of dynamics. The old geom- 



INSTRUMENTS OF INVESTIGATION. 25 

etry, both synthetic and analytic, is a mere infant 
compared with it. No one is now considered half 
equipped for astronomical research unless he can 
wield this splendid instrument. Taking certain 
facts given by observation, together with the New- 
tonian law of gravitation that every particle of 
matter attracts every other particle with a force 
proportioned directly to its own quantity of mat- 
ter and inversely to the square of the distance 
between them — taking these as its fulcrum, the 
Calculus has proved itself more than the lever of 
Archimedes ; for that moves only one world, this 
moves all the heavens. 

To see the feats of this Calculus makes one 
think of days of enchantment. I have a supreme 
confidence that none of you have ever heard this 
Arabian history of what anciently happened to 
one of the Genii. It seems that this good mon- 
ster, who was as tall as a mountain and as strong 
as an earthquake, had, on a certain occasion, 
amused himself by endeavoring to squeeze his 
huge figure into a little enchanted black bottle. 
At last he succeeded. Suddenly the cap flew 
down and he was caught. Some thousands of 
years afterwards, a poor man, while at his work 
one day and thinking how hard it was with his 
best efforts to make a living, stumbled on this 
same little bottle. " Let me out — let me out! " 
cried the bottle in a half- suffocated whisper. 
" Can't do it," quoth the man, at once aware of 



26 FIRST IECTURE. 

his good fortune, — "can't do it." "I will do 
any thing you want if you will," begged the pris- 
oner. " Will you take away that great mountain 
between me and the city — will you turn my lit- 
tle tent into a palace — will you fill it with gold 
and precious stones —will you promise by all that 
is sacred to Genii, by the Prophet and Alcoran 
and Allah ? " " Yes, I promise." After some 
difficulty, the man managed to find out the secret 
of the spring-cap, and lifted it ; when, swift as an 
arrow, out rushed a puff of blue vapor, which 
gradually expanded till, as tall and broad as 
Mount Shahak, it took the form of a winged 
man. Without any ado, the monster took up 
the mountain in his arms and walked off with 
it a few steps, say a hundred miles or so, and 
threw it down in a valley behind Bagdad, where 
he who chooses can see it at this day. Then 
stepping back, he caught up the little tent 
and threw it up into the sky out of sight, say- 
ing, " Come down great, come down precious." 
In a few minutes, a cloud came settling down 
on the spot ; and, as it slowly broke away, 
the man discovered minarets and towers and, at 
last, a whole gorgeous palace of marble, fit for 
the Leader of the Faithful himself. Then the 
Genius plucked a leaf from a majestic palm that 
waved proudly by the portal and wrote certain 
strange characters on it with his finger. Tearing 
it hit? small pieces, he puffed them away in every 



INSTRUMENTS OF INVESTIGATION. 27 

direction with his breath. Immediately, long lines 
of Ethiopian slaves were seen coming up from all 
quarters, with immense stuffed sacks on their 
shoulders (I suppose twelve men in these degen- 
erate days could scarcely lift one of them) ; and, 
as eacli entered the palace and laid his sack on 
the floor, he laid himself down also by the side 
of it and became another sack as large and full 
as that he had brought. In a short time, the 
palace was full, from foundation to roof. "Come 
and see," said the Genius. Lo, gold Alraschids, 
Almansors, and Motasseins ! Lo, carbuncles and 
sapphires and diamonds filled every apartment ! 
" Have I kept my promise — am I free ? " — "Ay ; " 
said the enraptured fellow, " and well have you 
deserved your liberty." — "To tell the truth," 
quoth the spirit, " I have been so long in that 
little black bottle that I think I had rather stay 
there than anywhere else. When you want me 
you will know where to find me." So, without 
any more ceremony, he doubled himself up and 
squeezed into the bottle again. Was not his 
name Radib ? Was not that poor man the same 
Emir Alabdes by whom the Caliph Motassem (for 
whom Allah be praised), with ten thousand of his 
attendants, was so sumptuously entertained at 
his marble palace, in the 180th year of the 
Hegira ? 

I say, it makes one think of such an Arabian 
Nights 7 story, when he looks at some of those lit- 



28 FIRST LECTURE. 

tie equations out of which Clairaut and La Place 
and others have managed to evoke such prodi- 
gious dynamics as have sufficed to enrich them- 
selves and their race with uncounted treasures 
of fame and truth ; as have sufficed to remove 
mountains from the path of astronomy, and con 
vert her humble tent into a spacious palace filled 
with unprecedented gems of the plundered sky. 
How much does yonder star weigh ? When will 
yonder hairy star come back ? Suppose five worlds 
launched in vacancy from a given position, with 
given directions and velocities, where will each be 
twelve thousand years hence ? Such questions as 
these which men would once have despaired of 
answering, and even greater questions the terms 
of which cannot properly be assumed as intelli- 
gible at this point, the Calculus has conquered 
and dragged in triumph at its chariot-wheels. 
And still this prince of good Genii is at the ser- 
vice of astronomers. He does not care for his 
liberty. He still likes to take up headquarters 
in the little black bottle of a differential equation. 
When his friends want something great done they 
know where to find him. And I should not be 
surprised to see the day when I can tell of new 
feats of his doing, quite as prodigious as any jot 
recorded. Do not doubt it — he is as strong as 
ever. The race of Eulers, Newtons, and La 
Places, is not yet dead. Gifted men are busily 
learning the secret of the spring-cap. And, some 



INSTRUMENTS OF INVESTIGATION. 29 

fine morning, men shall read on the bulletin boards 
of science of new mountains removed, new palaces 
built, new whole commissariats of golden and dia- 
mond truths established for astronomy by the re- 
doubtable Radib of the Differential and Integral 
Calculus 



II. 

THE SKY. 



31 



II. The Sky. 

i. ASPECT 33 

2. NATURE 3 g 

3. NATURE OF CONTENTS 43 

4. ARRANGEMENT OF CONTENTS 49 



32 



SECOND LECTURE. 



THE SKY. 



I AM to explain what discoveries have been 
made in the distant sky. To do this to the 
best advantage, we must have a picture of the 
sky, with its leading aspects and names, fresh in 
our minds. 

So let us imagine this structure unroofed, and, 
indeed, well taken down on all sides. And, to- 
night, let us further imagine that some tall Genius 
is kind enough to brush away with his besom the 
envious clouds — those ancient and unutterable 
enemies of the astronomer. We seem to be at 
the center of an immense hollow, half-globe, on 
the distant surface of which appear the heavenly 
bodies. If it were day, we should see on that 
remote concave the yellow sun : it being night, 
we see, instead, a multitude of stars and the moon 
with its silver crescent. Watch the host for a 
little behind some building, and you may satisfy 
yourself that they are all in motion towards the 
west ; that is to say, are all revolving about a 

3 33 



34 SECOND LECTURE. 

line drawn through where you are sitting and 
a point due north, but elevated about 40° above 
the horizon. Notice that very bright white star 
low in the west : that is Venus, named after 
the Greek and Roman goddess of beauty. Yon- 
der, almost overhead, is another star, of scarcely 
inferior brightness but of more masculine hue: 
that is Jupiter, named after the king of the clas- 
sical divinities. East of the zenith, about one 
third of the way down, you may perceive a much 
smaller star of ruddy light — Mars by name — 
appropriately called from the bloody god of war. 
Do you see that small star, just visible to the 
naked eye, almost on the eastern horizon ? Well, 
that is Saturn, named from the father of the prin- 
cipal gods, and sufficiently dim to represent one 
who is said to have had the very unfatherly and 
unhandsome trick of eating his own children. 
These stars, and many others which are never 
seen without a glass, are called planets, because 
they wander about greatly on the sky. Besides 
these, are certain other bodies, seen only occa- 
sionally, which are still greater wanderers — 
comets so-called, hairy stars — a denser part 
more or less bright, surrounded by a haze which 
often is found expanded into a pale streamer of 
prodigious length. 

All others stars bear the name of fixed stars, 
because, to ordinary observation, there is little 
or no apparent change in their positions with 



ASPECT. 35 

respect to each other. Some of these bodies 
are very conspicuous, real princes for shining, 
and so, from time immemorial, have been hon- 
ored with proper names. There, for example, is 
one nearly as brilliant as Yenus herself — Sirius 
— with a ray as frosty and keen as ever glanced 
from an iceberg ; another, Aldebaran ; another, 
Capella. Nearly half way up the northern heaven 
is a star by no means bright, but which has been 
on men's lips and in their eyes oftener than any 
other star whatever — the star by which ships 
have steered, and armies marched, and bondmen 
fled — the North Star. Count some twenty of 
the brightest of the fixed stars on the whole 
sphere : these astronomers call stars of the first 
magnitude. Count some sixty of the next bright- 
est : these are of the second magnitude. Some 
two hundred of the next order of brilliancy : 
these are of the third. Six <%iers of magnitude 
are visible to the . naked eye : ten orders more 
include those seen by the telescope. 

i Notice the unequal distribution of the stars 
on the sphere. Some are solitary, some in little 
groups and clusters, some in dense masses that re- 
semble white clouds; while, among others, there 
seem no well-defined natural divisions — they 
seem sown broadcast and carelessly on the vault. 
That group of five stars forming the letter V is 
called the Hyades — rainy Hyades, said the an- 
cients. That cluster £ little further to the west 



36 SECOND LECTURE. 

is the Pleiades — Job's Pleiades, with their sweet 
influences. And here, stretching across the whole 
hemisphere, like a white fog-bank with torches in 
it, is the well-known Milky Way which the old 
poets tell us was inadvertently made by Hercules 
when an infant. Other objects of the same gen- 
eral appearance are disclosed by the telescope 
in various quarters of the heavens — nebulae, so 
they are called. 

These are natural divisions of the heavenly 
bodies. There are others not so natural, called 
constellations. The ancients (no one knows how 
ancient they were), with not a little help from 
the moderns, pictured the celestial sphere all 
over with figures of men and brutes and other 
objects, so as to show almost as extensive a men- 
agerie as was collected in Noah's ark : indeed, 
the very ark itself is there ; at least Noah's dove, 
and we may reas^Sably suppose the ark to be 
not far off. There are bears and lions and do- 
mestic animals and birds and fishes and reptiles, 
interspersed with warriors and nymphs and cen- 
taurs and flying horses, all dovetailed into each 
other so as to include within their outlines nearly 
all the stars. If the leg or arm of a human figure 
could not be so disposed as to cover certain stars, 
a snake, under the sonorous name of Draco or 
Hydra, was slipped in to wind in and out till the 
crooked feat was accomplished. Yery seldom any 
resemblance can be traced between the constel- 



ASPECT. 37 

lations and the various objects after which they 
are called. But judge for yourselves. Around 
the North Star as a center, describe a circle that 
shall just touch the horizon. Within this circle 
are the Great and Little Bear, an immense Dra- 
gon, royal Cepheus with a crown on his head and 
a scepter in his hand, the helmed head and lifted 
falchion of Perseus, and on her chair, with a palm 
branch in her hand, queenly Cassiopeia. Would 
you think it? Around the point directly over- 
head, describe another circle that shall just touch 
the other. Within this new circle we have, tow- 
ards the north, beauteous Andromeda, with fetters 
on her dainty hands and feet ; west, Pegasus, the 
winged horse ; over our heads, Aries the Ram ; 
next east, a sort of celestial Spain — for there is 
shaggy Taurus in full career with horns leveled 
at giant Orion, who, sworded and belted, with a 
lion-skin in one hand and a club in the other, is 
just in the act of dealing the monster a rousing 
blow between the eyes that will undoubtedly make 
him see stars. Could you have thought it — such 
dignified personages, such delightful nymphs, such 
illustrious heroes, such magical creatures, such 
stirring tourneys and bull fights, all up and down 
the arches of the sky ! However, these fanciful 
figures answer a very good purpose for classify- 
ing and describing the heavenly bodies. They 
distribute them into celestial nations and em- 
pires. 



38 SECOND LECTURE. 

Provision is made for still further descrip 
tion of each celestial district, to any degree of 
minute accuracy that may be desirable. For 
many purposes, it is sufficient to tell what con- 
stellation a star is in. If we have occasion to 
be a little more precise, we can say in what part 
of the constellation it may be found, as in the 
neck of Taurus or head of Andromeda. To pro- 
vide for still greater precision of statement, as- 
tronomers Have named the stars in each constel- 
lation according to their ^apparent brightness. 
The brightest is called after the first letter of the 
Greek alphabet, Alpha ; the next brightest, after 
the second letter, Beta; and so on through all the 
letters. When the Greek alphabet is exhausted, 
the Roman is used in the same wa} r . If both al- 
phabets are not sufficient to take account of all 
the stars, our common numerals are resorted to. 
Thus we speak of Alpha Leonis, a Virginis, 61 
Cygni. But it is not always enough, in making 
a map of a country, to draw its boundaries and 
set down within them the various cities and towns 
of all sizes, in something like their relative posi- 
tions: some geographical purposes require that 
you state also their longitudes and latitudes; that 
is to say, their distances due east or west, and 
their distances due north or south of a given 
point on the earth. So, for some astronomical 
purposes, it is not enough to bound a given con- 
stellation and set down its stars in nearly their 



ASPECT. 39 

relative places, with their names. We requ re to 
know the longitude and latitude of each. star. 
We must know how far it is from a certain 
great circle drawn northerly and southerly on 
the sphere, and how far also from another great 
circle drawn at right angles to the other. From 
very remote periods, astronomers have been en 
gaged in getting this latter information. Hip- 
parchus made out a catalogue of nearly all the 
stars visible to the naked eye at Alexandria, giv- 
ing the latitude and longitude of each. Herschel, 
La Lande, Mayer, and others, have constructed 
similar catalogues, but giving the places of the 
stars with much greater accuracy. 

We have before us a general picture of the 
celestial sphere, with the more usual names and 
classifications of the objects that shine upon it. 
I am now prepared to state what discoveries have 
been made. What is this seeming immense hol- 
low globe of the heavens ? People once thought 
that the appearance was reality — that they were 
surrounded at a great distance by an immense 
shell of crystal, to which all the heavenly bodies 
were fastened. At a later period, most scholars 
thought there were several of these spheres: each 
carrying heavenly bodies, and each having a mo- 
tion peculiar to itself. But now we know that 
there is nothing of the sort above and around 
us. The celestial sphere is nothing but indefin- 
itely extended space, made to appear colored at 



40 SECOND LECTURE. 

times by the hue, and to appear rounde i always 
by the shape, of oir atmosphere. There is noth- 
ing solid yonder to which the celestial bodies can 
be attached. They are absolutely hung on noth- 
ing — though Milton ventures to take poetic 
license, and hang one orb, at least, by a golden 
chain. This idea of unsupported heavenly bodies 
was quite too hard for the remote ancients : they 
must have spheres, and, not a few of them, an 
elephant and a tortoise to hold up the earth and 
heavens. But, finally, it filtered through the ap- 
prehensions of people that such supporters must 
themselves need support quite as much as a star; 
also, that no one ever saw them, or otherwise 
credibly knew of their actual existence. So they 
were quietly dispensed with. And now nothing 
remains but the infinite space, which we certainly 
know to exist, and the stars which we certainly 
know to exist in it. 

Popularly speaking, this great space which en- 
virons us on all sides, and contains the heavenly 
bodies, is empty. It is substantially a vacuum. 
The ancients said that Nature abhors a vacuum : 
if so, she has plenty of abhorring to do. There 
is no atmosphere pervading space : we could 
not breathe in its mid-intervals one single mo- 
ment ; there is nothing there that our senses 
could perceive. As we ascend from the earth, 
wo find the air gradually become thinner ; and La- 
Place has shown, that, after a few miles, it must 



NATURE OF THE CELESTIAL SCENERY. 41 

cease entirely. Beyond that point, very large 
solid bodies, though moving with enormous ve- 
locity, are found to encounter not the smallest 
perceptible resistance. Their places, as computed 
on the supposition that they move in a vacuum, 
are such as we actually find them. At the same 
time, there is reason to believe that the vacuum 
may not be absolutely perfect. Certain facts 
which have come to light in late years have con- 
vinced many astronomers that we must allow 
the existence of an exceedingly dilute form of 
matter pervading space. It is nothing that we 
could detect in the ordinary, sensible way : we 
could not weigh it, nor see it, nor receive sounds 
through it ; could not feel it, should we strike 
our hands through it with our utmost force. 
Such a mere nothing is it. It is only when some 
very light body goes rushing through it, at the 
rate of thousands of miles an hour, that its pres- 
ence becomes sensible in resisting somewhat the 
motion. 

If we could visit mid-space, it would seem a 
perfect void, also dreadfully cold and dark and 
silent. The higher we go into our atmosphere, 
the colder it becomes. All mountain summits, 
above a few thousand feet, are covered with per- 
petual snow. Persons ascending in balloons at 
last reach a cold that is intolerable. They evi- 
dently approach the confines of an eternal winter,, 
that, for silence and motionless fierceness, laughs 



42 SECOND LECTURE. 

to scorn all that we have of arctic and an- 
tarctic. 

According to the calculations of Sir John Her 
schel, we have only to go fifty miles from the 
earth's surface to reach — 132° Fahrenheit. Could 
we suddenly set down any moist thing at this 
point, it would instantly explode like a pistol, 
though without sound (for mid-space is sound- 
less as well as matterless), and turn to stone as 
if touched by a magician's wand. And if, at this 
short distance from the earth and sun, space is so 
cold, what must it be in those remote vacancies 
where the sun shows as a mere star ? In thought, 
we sail away most comfortably among the con- 
stellations, without furs or overcoat ; and per- 
haps our fancies make nothing of stopping whole 
hours in mid-heaven, leaning against the chair 
of Cassiopeia, or grasping the horns of Taurus, to 
admire the glory of the trooping stars ; but one 
real bodily expedition of the sort would forever 
cure us of such fancies. Perhaps of some others 
also ; for, when our thoughts go yachting it 
through space, they are very apt to take with 
them, not only our genial parlor temperature, 
but also our pleasant earthly light and colors. 
But, in point of fact, the starry spaces are awfully 
dark. Those who visit the higher regions of 
our atmosphere, by mountains or balloons, tell us 
that the pleasant blue gradually passes into an 
intense black. At last, the stars glitter on a 



NATURE OF THE HEAVENLY BODIES. 43 

background of perfect jet. To an observer out 
in mid-heaven, the whole sphere would seem muf- 
fled in a horrible pall, save just at the points 
where the heavenly bodies are. He would have 
the impression of not being able to see an inch 
before him. He would see sun, moon, and stars 
all at the same time ; but they would look as if 
hissing on a sea of ink. The blackness would 
seem solid enough to be cut with a knife. An 
Egypt in the sky would seem to him to have com- 
pletely overrun its Spain, and indeed its whole 
atlas of celestial empires. And should he try to 
express his feelings, and to say, " How awful is 
this blackness! " — "How glorious are these lu- 
minaries ! " — no sound, nor specter of a sound, 
could issue from his shouting lips. 

Such is the " House I live in " of the heavenly 
bodies. What are the heavenly bodies them- 
selves — what this sun, this moon, these planets 
and comets and fixed stars and nebulae? 

In remotest times, very likely, men thought 
them distant heavenly torches, or openings 
of various sizes through the sky into an ocean of 
glory beyond. In process of time, they came to 
be very extensively regarded as intelligent beings 
— gods and goddesses, also human beings raised 
to the skies on account of illustrious merit, or, 
what was not always the same thing, the favor 
of the divinities. The sun was Apollo, god of 
fiery arrows ; the moon was Diana, goddess of 



44 SECOND LECTURE. 

the silver bow ; and so on, until the sky was one 
great Parliament House of deities in everlasting 
session. Worship was paid to the shining crowd ; 
to them incense rose, hymns were chanted, and 
victims bled. In civilized countries of modern 
times, people are far enough from such views of 
the nature of the heavenly bodies : multitudes do 
not even trouble themselves to have any views 
whatever on the subject. They have never put 
the question to themselves, " What are they — 
those bright lights above us ? " Accustomed to the 
sight from infancy, busied in their digging and 
buying and selling, it has never occurred to them 
to be curious as to the nature of those far-off 
luminaries. They are content to have the use 
of them — to work by the sunlight, to walk by 
the moonlight,. to steer, and perhaps to steal, by 
the starlight. In this respect, they are inferior to 
many in the remotest and rudest ages. And yet 
the question has long been well answered, and 
the answer is in possession of tens of thousands 
on all sides of them. What are the heavenly 
bodies ! Not lamps, not apertures through which 
glory shines, not personages ; but immense mass- 
es of unintelligent matter, some self-luminous, 
and the rest shining by reflected light. It is 
found that the light coming direcly from a can- 
dle, or other sell-luminous object, differs by a cer- 
tain property from the same light after it has 
undergone reflection. This fact enables us to 



ascertain easily that a part of the objects in the 
sky shine by reflected light, while the rest are 
self-luminous. The sun, and fixed stars, and 
nebulas are found to be self-luminous ; the 
moon, planets, comets, and zodiacal light shine 
only by the light that comes from these. If a 
man is confronted by what purports to be a 
ghost, he pronounces it well-authenticated flesh 
and blood just as soon as he sees that it casts a 
shadow.; so, just as soon as we find that the 
heavenly bodies emit and reflect light, we know 
that they are true matter; and, so far as we 
have been able to observe this matter, it has the 
appearance of that which composes our earth. 
If the moon is looked at through a telescope, we 
see a rugged surface of mountains and valleys. 
In regard to the other bodies in the sky, the glass 
does not serve us as well ; but the telescopic 
aspect of most of the planets gives none the less 
decidedly the impression of an earth-like surface. 
But the heavenly bodies are not only masses of 
earthy matter : they are masses of immense size. 
They look small to us, it is true — the sun and 
moon occupying no larger space in your eye than 
does the crown of your hat at the distance of a 
few feet, and most of the stars showing as mere 
needle-points. They do look very small, most 
certainly ; but so the great earth would if we 
should go very far away from it. The earth is 
so large that we can travel upon it for months 



46 SECOND LECTURE. 

and years without crossing our track ; and yet, 
should we go off into space from it, this immense 
bulk would gradually lessen on the eye till at 
last it would appear no larger than the smallest 
star. Though the dog bays at the moon as if 
it were within hearing, though the savage thinks 
that he could almost bring down the sun with his 
arrow, though so intelligent a person as Yirgil 
tells us of a personage who brushed the stars 
with his sublime head, yet it is very easily dis- 
covered that the nearest of the heavenly bodies 
must be thousands and thousands of miles away. 
This is proved by the fact that only a few of them 
appear to change their places on the sky at all in 
consequence of any change, however great, in our 
position, and these few only in a very slight de- 
gree. A few steps will change the place on the 
heavens of some near objects a whole quadrant : 
but yonder mountain, twenty miles away on the 
horizon, would scarcely seem to stir should you 
walk an hour perpendicular to the line of its 
direction. Now, as to the heavenly bodies, it is 
found that one might travel thousands of miles 
on the earth, without shifting the apparent place 
of most of them on the vault in the slightest — 
without shifting the apparent place of any of 
them, save by a very trifling amount. So it is 
plain that they must be at a very great distance 
from us. Why, if a body were displaced on the 
sky to the am. unt of the moon's apparent diame* 



DISPOSITION OF THE HEAVENLY BODIES. 47 

ter, by our going a thousand miles on the earth, 
it must be a hundred thousand miles away ; and 
there is not a body in the whole heaven that would 
undergo any thing like that displacement were 
we to remove such a distance. So we must con- 
clude that all the heavenly bodies are immensely 
remote from us, and so of immense magnitude. 

How are these great masses of matter actually 
disposed in space ? According to some principle of 
orderly arrangement, we should presume. The Su- 
preme Cause is no friend to confusion. Still, what 
the celestial order really is, is not easily discover- 
able. There is, to first view, no system whatever 
in the distribution of large portions of the heavenly 
bodies. It is as if the Genius of disorder had sown 
them. In other parts, there are appearances of sys- 
tematic arrangement; but then the question arises, 
Is the apparent arrangement the real one ? Can 
I say that two stars are actually near each other 
in space, because they appear near each other on 
the sky ; or that other two stars are remote from 
each other, because one appears in the east, while 
the other is seen in the west ? Not as long as I 
find, that, by putting myself between two trees 
only ten feet apart, I project them on directly op- 
posite points of the heavens ; not as long as I 
find that the tree which is only ten feet from me, 
falls on the sky at the same point with yonder 
mountain which is twenty miles away. So there 
was no small difficulty in ascertaining the real 



48 SECOND LECTURE. 

plan among the celestial bodies ; and, in fact, it 
was not ascertained till after long ages of obser- 
vation and study. But persuaded, as thinking 
men were, that there must be system everywhere 
within the domains of the Supreme Wisdom ; 
well aware, as most of them were, that apparent 
confusion, from unfavorable points of view, often 
covers a system of exactest order — they did not 
give over to inquire. At last they found the fa- 
vorable stand-point which laid open the whole 
mystery of the celestial arrangements. The lamps 
of a city, as one approaches it some evening, ap- 
pear a mere chaos of bright points ; and yet that 
city is Philadelphia, where streets cut streets des- 
perately at right angles and all the lights gleam 
on the sides of perfect squares. And they seem 
so to the same man, when, turned aeronaut, his 
balloon has shot him up thousands of feet over the 
centre of the city. He has now found the true 
point of view. An army engaged in battle seems 
an inextricable maze to a looker-on from the same 
plain — men projected on and crossing men till all 
individual outlines are lost — and yet here are all 
the parts of a host, from corps to companies, each 
under its own leader, in unbroken array and ad- 
mirable discipline, pressing forward on victory to 
the rhythm of exulting trumpet and drum as only 
Napoleon and Austerlitz know how to pour them 
along. And it seems so to the same man just as 
£Qon as, arrived at yonder lofty hill-top, he mingles 



DISPOSITION OF THE HEAVENLY BODIES. 49 

with the Emperor's staff and looks down on the 
whole scene. He has now the true point of view. 
So, at last, astronomers have found their true point 
of view. They look from over the beaming city. 
They gaze down on the rushing army. And now 
the whole celestial economy of arrangement stands 
unfolded. What is it ? The system of arrange- 
ment is this : — 

1. A body, not self-luminous, has one or more 
like bodies revolving around it. There are many 
such systems, which we will call satellite -sys- 
tems* 

2. Several of these primary systems form a still 
larger neighborhood, and revolve about a self- 
luminous body, like the sun. There are many 
such systems, which we will call planet-systems. 

3. Several of these planet-systems form a still 
larger neighborhood, and revolve about a com- 
mon point within it. There are many such sys- 
tems, which we will call sun-systems. 

4. Several of these sun-systems form a neigh- 
borhood still larger, and circulate about one point 
within it. There are many such systems, which 
we will call group-systems. 

5. Several of these group-systems unite in a 
still larger neighborhood, and in revolving about 
a common point within it. There are many such 
systems, which we will call cluster -systems. 

6. Several of these cluster-systems combine into 
ai_:ther system still grander, whose centre of mo- 



50 SECOND LECTURE. 

tion is also common to all its members. There 
are many such systems, which we will call ne- 
bula-systems. 

7. Finally, all the systems of space, composing 
one great neighborhood that embraces all other 
neighborhoods, revolve around one motion-centre 
of the creation. This we will call the universe- 
system. 

You see that it is a wheel within a wheel. Cer- 
tainly, the ' height of that last, all-embracing wheel 
is exceeding dreadful.' Each order of systems 
includes all the orders below it ; and each pri- 
mary system has at least as many revolutions as 
there are different orders. It is very like the ar- 
rangement of human society. First, we have the 
elementary group of the family, revolving about 
the home ; then several families, making a town, 
revolving about its central village ; then several 
towns, making a county, revolving about its county 
seat; then several counties, making a State, revolv- 
ing about its State capital ; then several States, 
making a nation, revolving about the national 
metropolis ; then several nations, making a world, 
revolving about the political centre of humanity, 
which once was Rome, which now is — shall we 
say London or Paris or St. Petersburg or Wash- 
ington ? 

Take another illustration ; for it is important 
to have this matter familiar. In these warlike 
times, i\ is hard to resist dealing in warlike ill us- 



DISPOSITION OF THE HEAVENLY BODIES. 51 

trations : oesides, it may fairly be presumed that 
they will be understood with special facility. Ima- 
gine the encampment of a great army. On enter- 
ing it, the order in which the tents are disposed 
does not readily appear. But, on examination, 
we find that there is a very rigid system of ar- 
rangement, and that this is it, First, the camp of 
the company about its captain, separated by a 
plain interval from all other company -camps. 
Next, expanding around this, is the camp of a 
regiment about its colonel, separated by a still 
more marked interval from all other regiment- 
camps. Then, expanding around the regiment, 
is the camp of the brigade about its brigadier, 
separated by an interval still more decided from 
all other brigade -camps. Further, expanding 
around the brigade, is the camp of the division or 
corps about its major-general, separated by an 
interval still broader from all other corps-camps. 
Lastly, expanding around the corps, is the whole 
encampment of the grand army about its general 
or marshal or monarch. See here a picture of 
the great encampment of the sky! I say "en- 
campment ; " for, to one watching the sky for a 
short time, every thing seems stationary. But, 
really, the sky is not a camp. It is rather a glo- 
rious parade ground, full of motion, full of or- 
derly, systematized motion — a flaming bannered 
field on which the various celestial powers are 
going through their various related evolutions 



52 SECOND LECTURE. 

under their respective leaders — companies of 
stars maneuvering under star -captains ; regi- 
ments, brigades, divisions, whole hosts of stars, 
manoeuvering under star- chiefs of as many as- 
cending grades of rank and splendor. Hail, host 
of heaven ! Hail, glittering rank and file ! Hail, 
gorgeous commanders in golden mail, and shin- 
ing far o'er the field ! Veterans all, though un- 
scarred, as far as we can now see, — all hail ! for, 
as we shall soon find, such brilliant equipment, 
such skillful commanding, such perfect obeying, 
such complicate wheeling on exactest time and 
admirable step, was never seen in any terrestrial 
army. 

But you would like the evidence that such is 
the arrangement of the heavenly bodies. It is 
observed that every thing on the earth is heavy. 
We never take up any thing about the earth, 
whether great or small, whether this sort of mat- 
ter or that, without finding it to have more or less 
weight. That is to say, the earth attracts it, or it 
attracts the earth, or, perhaps, both mutually at- 
tract. Newton, on thinking the matter over (we- 
know how it happened, under the famous apple- 
tree, and how, as the apple came down, the thought 
of the philosopher went up) , concluded to adopt 
the last view, and to suppose that an attractive 
force, developing itself equally in all directions, 
and extending to all distances, belongs to every 
atom of matter, terrestrial and celestial. On the 



DISPOSITION OF THE HEAVENLY BODIES. 53 

basis of this assumption, lie was able to prove, 
mathematically, that every body must attract 
every other body with a force proportioned di- 
rectly to its own quantity of matter, and inverse- 
ly to the square of the distance between the bodies. 
If you double the amount of matter in a body, 
you double its attractive force ; if you double its 
distance from another body, you quarter its at- 
tractive force on that body. With this law, he 
proceeded to demonstrate, by the most rigorous 
of mathematics, that, if two or more free bodies 
in space form a neighborhood, they must instant- 
ly rush together, or they must all revolve about 
their common centre of gravity ; meaning, by 
this common centre, that point among them 
where their several attractions just balance each 
other, so that a particle at that point would have 
no tendency to move. The fact that such bodies 
are found apart, after an existence of thousands 
of years, will then be proof that they are all re- 
volving about their common centre of gravity. 
Hence, if several celestial bodies are found con- 
tiguous, as compared with others, we must infer 
that they form a system of revolution by them- 
selves ; if several of these minor systems are 
found contiguous, as compared with others, we 
must infer that they compose a still larger revolv- 
ing system ; and so on. Or, if we find certain 
heavenly bodies forming together a system of 
revolution, we must infer their relative contiguity 



54 SECOND LECTURE. 

to ea;h other in space. We need only to estab- 
lish, by observation, the actual existence of either 
such celestial neighborhoods as have been de- 
scribed, or such related motions as have been 
described, in order to establish the existence of 
both. Now we can always do the one or the 
other. 

But one suggests, " There is an assumption at 
the bottom of this argument. Newton assumed 
that attractive power, flowing out equally in all 
directions and at all distances, belongs to every 
particle of matter, celestial as well as terrestrial. 
Where is the proof that this assumption is cor- 
rect ? " I answer, that we have no other proof 
than is involved in the fact, that, after very long 
trial, the results flowing from the assumption have 
not been contradicted by any known fact, while 
they wonderfully harmonize with and explain 
all the leading astronomical phenomena. A man 
computes, by the law of gravity, just where in the 
sky a planet or comet ought to be found at a given 
time ; and, when the moment comes, we look at 
the spot, and lo ! the body is there. Feats of this 
kind have been so numerous ; the law of gravity 
has been tried for the explanation of such hosts 
of astronomical facts, and with such invariable 
and brilliant success — that astronomers have at 
last come to rely on its truth with unbounded 
confidence. And they are philosophically obliged 
to do so. The original assumption stands proved 



DISPOSITION OF THE HEAVENLY BODIES. 55 

by an overwhelming experience. It his been 
gradually established by an immense induction of 
particulars. And now men can not refuse confi- 
dence to it without rejecting that Baconian phil- 
osophy which lies at the foundation of all our 
modern science. 

That you may still better realize the weight of 
this proof, let us suppose a case. Imagine an im- 
mense castle, with every gate and door about it 
locked. You are informed, on authority that you 
can not question, that there once existed a single 
key which could open every room and closet and 
drawer of the edifice ; but, alas ! it has long been 
lost. One day, in walking about the premises, 
you stumble on something that looks very much 
like a key, an ancient key, a key that on pressure 
of a spring can be made to take almost any shape. 
Well, you can not help your thoughts : they do at 
once suggest to you that, perhaps, you have been 
fortunate enough to fall in with the long-lost won- 
derful bit of iron that can let you into every part 
of the sealed castle. Still you could be surer — 
a great deal surer ; in fact, you have very serious 
fears lest, on trial, your key shall prove a mere 
pretender. Tremblingly you try it on the court- 
yard gate : after some trouble, the gate flies open. 
Your courage rises. Eagerly you approach the 
main entrance, and try that : after a while, that 
too gives way, and you enter the castle proper. 
You are now still more sanguine tha" your key is 



56 SECOXD LECTURE. 

the true one. Still, it may fail at the very next 
trial. So you proceed to question another door, 
and another, and still another ; with continually 
augmenting confidence as success follows success. 
You find very great difficulty at times, both in 
adapting and turning the key ; you have to de- 
lay before some doors a long time; but, in nearly 
every case, success comes at last. And now, on 
counting up, you find that your key has opened 
for you all the main rooms in the castle ; in fact, 
all that you have seriously and patiently tried — 
doors of oak, doors of iron, doors with locks of 
the strangest and most intricate pattern — it has 
conquered them all. At length you are perfectly 
satisfied. You would not give the snap of your 
finger for any additional evidence that your key 
is the genuine. Should some one come to you 
and say, " My dear sir, are you not a little too 
credulous — do you not give your faith in this case 
a little too easily — as for me, I am not quite 
sure that there is no mistake, am afraid you 
have not the true key yet!" — you would be 
tempted to reply, " My very wise sir, when did 
you escape from the asylum?" Such a man is 
beyond argument. 

Xow, this is just the case that has been pre- 
sented to astronomers. Here is the immense sky- 
castle, that, from the beginning, has been fast 
locked up from men — a huge, inaccessible, inhos- 
pitable warrior-monastery. Men knew there must 



DISPOSITION OF THE HEAVENLY BODIES. 57 

be some clew to those mysterious cloisters — some 
key or keys that could match the wards of those 
innumerable locks. Where was it? None knew. 
It had never been seen from the beginning. Did 
the architect, as soon as the magnificent struc- 
ture was finished and carefully locked up, like 
the God of the "Night Thoughts," fling the key 
from the starred battlements far into the pitchy 
and bottomless abyss of space ? But no, this 
could not be ; and so men went to roaming about 
the purlieus of the heavens, looking for that lost 
Pleiad of a key ; and oh, how often, mean- 
while, did they throw longing, not to say despair- 
ing, glances at that stern, unrelaxing sky where 
such treasures of science were keeping eternal 
quarantine ! At last Newton, one of these seek- 
ers, stumbled on the law of gravity. Is this the 
key ? It has the look of one ; for it is seen at 
once to harmonize and explain many terrestrial 
facts. It looks like a multiple key ; for it is won- 
derful what a variety of great theorems may bo 
drawn out of this same law of gravity. As it 
were, you have but to press a spring to make it 
assume an almost endless variety of forms. So 
Newton's heart fluttered with hope — mere hope. 
Tremblingly he put his key to the test. What 
was his joy to hear that first ponderous bolt fall 
back? Success followed success; courage swelled 
on courage. Newton himself lived long enough 
to unlock several of the main gates of the heavens 



58 SECOND LECTURE. 

with his own bands. Encouraged by his success, 
many other strong and skillful hands grasped the 
victorious law of gravity and essayed other en- 
trances, — sometimes succeeding easily, and some- 
times with no small difficulty and delay, but nearly 
always succeeding. So it has gone on up to the 
present time — door after door opening — doors 
of oak, doors of iron, doors of brass, doors of gold, 
doors of the strongest look and lock-pattern, doors 
by scores and hundreds — they have gone on yield- 
ing, one after another, to the wondrous key, till 
now we may speak of the Open Heavens. " What, 
Earth and Moon open ! Have you unlocked their 
hundred-gated theory?" Yes: not a consider- 
able gate of that Thebes but has described a com- 
plete semi-circle. " What, Sun and Planets open ! 
Has your key of gravity set their thousand gates 
a swinging ? " Yes, swinging to their full capa- 
city — thanks to the dexterous and patient hand- 
ling of wedded observation and geometry. " What, 
Star Groups open ! They have a myriad of strange 
and ponderous gates; and have even these yield- 
ed?" Ask the Herschels and Souths and Bessels. 
Yes : even those wards are not too intricate to be 
traversed by the victorious tenons and tongues of 
the law of gravity ; and now, if you choose, you 
can step over the golden threshold of many a 
planetary sun, and see for yourselves the marvels 
within. " What, Clusters open ! What Nebulae 
open ! And now I say. Hail to the law of grav- 



DISPOSITION OF THE HEAVENLY BODIES. 59 

it/, if it can fling open to the gazing science of 
men those million-gated and doubly -locked re- 
gions ! Can it, indeed, do that topmost feat ? " 
Ask the Struves and Peters and Argelanders 
and Maedlers ; and have not we ourselves heard, 
with our own ears, the recoil -thunder of some 
bolts under the strong hands of these giants? 
Yes : I have myself seen some of those burnished 
gates shot back to the very wall, and the philoso- 
phers who accomplished the feat yet standing, 
key in hand, with flushed faces, gazing into the 
audience chamber and royal pavilions of that 
highest heaven of matter. God bless the key ! 
It is GENUINE. 



III. 

SATELLITE SYSTEMS. 



61 



III. Satellite Systems. 

Example — Earth and Moon, 

i. DIURNAL REVOLUTIONS 60 

2. MUTUAL DISTANCE 7 o 

3. SHAPES AND SIZES 71 

4 MUTUAL GRAVITATIONS 77 

5 MASSES AND DENSITIES 81 

6. ORBITS 84 

7. MUTUAL ASPECTS 87 



THIRD LECTURE. 



SATELLITE SYSTEMS. 

IN the last lecture I stated how the Heavenly 
Bodies are arranged in space. They are dis- 
tributed into neighborhood systems of at least 
seven orders. These are the Satellite Systems, 
the Planet Systems, the Sun Systems, the 
Group Systems, the Cluster Systems, the Nebula 
Systems, the Universe System. Each order of 
systems includes all the orders below it ; and the 
members of each system revolve about its center 
of gravity. I will now proceed to prove and in- 
terpret these systems in the order named. 

A Satellite System consists of two or more con- 
tiguous heavenly bodies which are not self-lumi- 
nous, and which revolve about their common cen- 
ter of gravity. There are many such systems ; but 
the most accessible and useful example which I 
am able to present is that of the earth and moon. 

It was long before men were prepared to reckon 
the earth among the heavenly bodies. It seemed 
at first view so different from them — so unshin- 

63 



64 THIRD LECTURE. 

ing, so like an indefinitely extended plain with 
solid foundations of endless depth. But further 
thought corrected this mistake. Whence come 
the sun and stars as they rise in the east, and 
whither go they as they set in the west ? It is 
clear that they pass, on the average, twelve hours 
out of the twenty-four under the earth. So the 
earth is really a body of finite though great ex- 
tent, lying loose in space — space under it, space 
over it, space all around it. Of course it must 
be so. As to the notion that the earth does not 
shine like the distant heavenly bodies, it is quite 
without foundation. Our world does not appear 
as brilliant, simply because we do not see it from 
out of the midst of the night as we do the moon 
and stars. They do not appear bright by day 
- — for the most part do not appear at all — it is 
only when they are in the light while we are in 
the dark, that they seem to us to shine. If, some 
evening, when your room is brilliantly lighted, 
you take your stand in the middle of it and try 
to look out into the street, you can see nothing ; 
but persons passing can see you and all your 
movements. To them you shine. And could 
we take ourselves away into that pitchy space 
that expands around us, till the earth should ap- 
pear no larger than the moon, it would appear as 
bright as that luminary. 

The earth shines like a star. It shines, Low- 
ever, only b; reflection. Just as soon as the 



SATELLITE SYSTEMS. 65 

light of the other heavenly bodies is shut off from 
any part of its surface that part becomes dark. 
In this respect the moon is like it. We notice 
that it is only that side of the moon that is toward 
the sun that is bright ; and so it happens that for 
the greater part of the time the great light that 
rules the night appears to us under a broken 
circle. Also, the fact already referred to, viz., 
that reflected light has a different property from 
that which comes to us directly, enables us to 
pronounce the moon a mere reflector. So neither 
the earth nor moon is self-luminous. They fulfill 
the first condition of a satellite system. 

Do they fulfill the second condition ? Are they 
contiguous to each other as compared with other 
heavenly bodies ? If so, the law of gravity proves 
that they both revolve about their common center 
of gravity. Now this matter of neighborhood is 
easily settled. Ask whether any other heavenly 
body shifts its place on the sky any thing like as 
much as the moon, in consequence of a given 
change in our place. By going four thousand 
miles on the earth we change the moon's place 
by about twice its apparent diameter. No other 
body in the heavens experiences the hundredth 
part of this change. The earth and moon, there- 
fore, form a neighborhood. Hence they must re- 
volve about their center of gravity. And being 
both heavenly bodies, shining by reflected light, 
they maks a satellite system. 



66 THIRD LECTURE. 

Now let us notice the chief facts which have 
been ascertained concerning this primary system. 
And, first, each member is found to turn around 
on itself. What makes the stars rise in the east, 
move uniformly across the sky in parallel lines 
without disturbance of their mutual positions, set 
in the west, and, at the end of twenty-four hours, 
appear in the east again ? The most simple ex- 
planation is that the earth turns around on one 
of its diameters from west to east, with a uniform 
motion, once in twenty-four hours, while we are 
held to its surface by the attraction of gravitation. 
Indeed no other explanation is admissible. The 
idea that we are the center of creation, and that 
all the host of heaven, at as many different and 
immense distances, have their motions so adjusted 
to each other as to make the circuit of the earth 
in exactly the same time, is altogether too cum- 
brous to suit either philosophers or practical men. 
Besides, such a system is irreconcilable with the 
law of gravity. If it is in the nature of things 
possible that the earth is the center of the uni- 
verse, it is not possible that all the heavenly bodies 
should so fly in the face of gravity as to revolve 
about this center — or rather an axis passing 
through it — in parallel circles, in precisely the 
same time or in any times. So we are bound to 
conclude that the earth moves about an axis 
within itself, and thus gives us the beneficent al- 
ternation of day and night. 



DIURNAL REVOLUTIONS. 67 

But why are we not sensible of this motion ? 
How is it possible that we can be whirled around 
so fast as the rotation of so large a body implies, 
and be a good part of the time, as people say, 
standing on our heads, and yet remain entirely 
uninformed by our senses of what is going on ? 
Why, every thing about us shares our motion ; 
even the atmosphere goes around as fast as we 
do ; there is no jolt nor jar — how should we 
know, except by seeing objects moving by us, 
that we are in motion, any more than does the 
man engaged in the fairest summer sailing ? 
Were he to shut his eyes, there is nothing in his 
sensations to show him that he is gliding along : 
were he to open them only on the yacht and its 
furnishings he would seem at rest: he must look 
away to the shore, and see the trees and houses 
slipping by. So we are rolled around the world 
so smoothly and equably that we have to look 
away to the stars to know that we are rolling at 
all. Noiselessly, without hitches, without tremors 
— it is the perfection of lubricated and luxurious 
progress ! The softest, downiest, springiest char- 
iot that ever went rolling over its McAdam, with 
a prince inside, is an earthquake compared with 
this natural omnibus in which we have taken 
passage. As to the prejudice which some persons 
feel against having their heads point in diametri- 
cally opposite directions at different hours of the 
day, I do not know what can be done for their 



68 THIRD LECTURE. 

relief, unless it be to assure them that they shall 
have tha privilege, during their daily somer- 
saults, of always pressing their feet against the 
ground and holding their heads aloft in the 
air. 

A single evening's watching of the stars is 
enough to show us that the axis of the earth 
points nearly at the North Star ; that the motion 
around it is easterly ; that it is a perfectly uni- 
form motion, just the same distance being made 
in the same time. So much a single evening can 
show us. But it would take a great many even- 
ings to show us another striking fact, none the 
less sure, viz., that the axial revolution is always 
accomplished in exactly the same time. It is on 
evidence that our day has not varied the hun- 
dredth part of a second for two thousand years. 
There has not been the slightest change within the 
long sweep of history and tradition. We must, 
however, allow one or two exceptions. " Sun 
stand thou still on Gibeon, and thou Moon in the 
valley of Ajalon ! So the sun stood still in the 
midst of heaven, and hasted not to go down about 
a whole day." The Chinese have a tradition that 
there was once a day of double the usual length. 
And the Greeks have a fable that may refer to 
the same thing — that the son of the Sun once 
persuaded his father to allow him to drive T ris 
fiery chariot for a day. The result was that such 
another Phaetonizing never took place. The met- 



DIURNAL REVOLUTIONS. 69 

tlesorae steeds ran away with the youth ; wan- 
dered up and dowii the sky, setting every thing 
in a blaze ; and did not reach the gates of the 
west — how could they — till a long time after 
they were due. So there has been a day of ex- 
traordinary length. The Bible-miracle, however, 
may have consisted, not in suspending -the mo- 
tion of the earth on its axis, but in simply bend- 
ing the rays of light from the sun and moon so 
as to continue the illumination, apparently from 
the same points of the sky, long after the bodies 
themselves had passed at their usual pace below 
the horizon. Certainly, one or two miracles 
aside, the length of our day has never changed 
by the breadth of a hair : the earth wheels about 
on its axis now in just the same period as at the 
creation. So we have a beautiful unit of time to 
carry along with us in our terrestrial journeys, 
though altogether too small for journeys astro- 
nomical. 

On looking at the moon, to find whether it also 
turns around on itself, first appearances are 
against it. Bring a telescope to bear on its face. 
We can see many striking objects, but no consid- 
erable movement among them. In case of a ro- 
tation we ought to see all such objects moving 
across the disc in parallel lines. But, instead of 
this, we find them substantially stationary. 
Strange to say, this very fact, which at first view 
seems conclusive against a rotation, is the very 



70 THIRD LECTURE. 

fact which establishes it. For, on second thought, 
you perceive that in case the moon does not turn 
on itself, whether we move around it or it moves 
around us, we ought in the course of a revolution 
to see it on different sides. The fact that we see 
but one side can only be accounted for by suppo- 
sing that the body turns around on one of its own 
diameters, just as fast as the other revolution is 
made, in the same direction and nearly in the 
same plane. We shall soon see that this revolu- 
tion consumes about twenty-seven days. This, 
then, is the time in which the moon turns com- 
pletely around on its axis. This is the moon's 
day. Its day and month are of the same length. 
I have said that the moon is greatly more 
displaced on the sky by a change in our place on 
the earth than is any other heavenly body. 
Hence I inferred that it must be greatly nearer 
to us. But that is not saying that it is very near ; 
indeed, it is not saying but that it is a matter 
of some millions of miles away. The fact is, that, 
though a neighbor, the moon is a very remote 
neighbor ; at least, according to such standards of 
distance as we use in our every-day affairs. But 
we must hasten to enlarge our common units 
both of space and time. Astronomical systems, 
we shall find, are laid out on a different scale 
from the neighborhoods of this world ; and miles 
and days make but a sorry figure in attempting 
to deal with the smallest of the mighty parishes 



DISTANCE BETWEEN THE TWO BODIES. 71 

of the sky. The moon is 240,000 miles away. 
And this is a very close astronomical neighbor- 
hood ; though hardly close enough to enable us 
to act the part of the good Samaritan to our 
neighbor, in case it should fall among thieves ; 
though hardly putting it within visiting distance, 
except for our thoughts, which have both the 
taste and the faculty for riding on beams of light 
and the Pegasus of poets. I say 240,000 miles, 
on the average, and in round numbers. One 
French astronomer, La Lande, goes to Berlin, in 
Prussia ; another, La Caille, goes to the Cape of 
Good Hope. One marks where he projects the 
moon on the sky at a given moment ; the other 
where he projects it at the same. They compare 
notes. Difference between the two projections 
found to be so many minutes and seconds. How 
far apart are the two stations ? So many degrees 
of latitude, and so many miles in a straight line. 
Nothing more necessary than to sit down, and by 
a simple calculation in triangles which any child 
well advanced in his arithmetic can perform, find 
the distance of the moon from the earth's center. 
The exact mean distance is found to be 238,545 
miles. 

Now let us turn our attention to the shapes 
and sizes of the members of this satellite system. 
And, first, each member has been found to be a 
round body, slightly flattened on two opposite 
sides. A ru ber ball slightly compressed between 



72 THIRD LECTURE. 

your two palms will represent the figu:*e. How 
round the sky looks ! Whoever has been at sea 
has noticed that the topmasts of ships are seen 
first, from whatever quarter they may come. 
Look at the drops of rain ; the beads of dew with 
which the spider-thread is strung, or which start 
from the brows of labor and terror ; the round 
shot, which, when a moment ago they left the top 
of the shot-tower, were one irregular mass of 
molten metal. Newton has proved mathemati- 
cally, that the particles of a body, if free to move 
under the influence of gravity, must always ar- 
range themselves in a globular shape. Now ge- 
ologists tell us that the particles which compose 
the earth were once in this free state ; that far 
back, before man's day, the entire solid, rocky 
world was in a state of fusion. We should there- 
fore expect to find it of a rounded figure. More 
than this. The earth revolves on an axis. The 
necessary effect of this rotation on a fluid mass 
would be to draw it in at the extremities of the 
axis — the poles so called ; and puff it out midway 
between these points — that is to say, at the equa- 
tor. But we are not left to this reasoning. 
Have not men sailed around the world by sailing 
always in one general direction, and without 
being sensible of any abrupt change of level ? It 
has been proved that the attraction of a round 
body on objects external to it is as if all its atoms 
were ctf ncentrated into one at its center. This 



SHAPES A2?D SIZES OF THE TWO BODIES. 73 

being so, if one would be nearer the center of the 
earth when at its pole than when at its equator, 
bodies ought to fall more rapidly as we pass from 
the one toward the other. They are found to 
do so. A pendulum descends with increasing 
speed as we increase our latitude ; and it has 
been found that the rate of increase in the motion 
is such that the pole must be nearer the center of 
the earth than the equator is, by a six-hundredth 
of an equatorial diameter. 

Now the moon is just another such body — 
rounded, but not a perfect globe. At the full, its 
disc appears as a complete circle ; and its apparent 
shape at other times — as crescent, half-moon, gib- 
bous — can only be accounted for on the supposi- 
tion that it exposes a globular surface to the rays 
of the sun. And, as it revolves about one of its 
own diameters, we conclude from analogy as well 
as from the demonstrated tendency of the atoms 
of all rotating bodies, that it is slightly flattened 
at the poles. 

Almost every one has himself moved about on 
the earth enough to satisfy him that it is a very 
large body. The man who has sailed around it, 
and at the end of his two or three years of voy- 
age finds himself where he started, does not need 
to consult his log-book to know that its circumfer- 
ence must be some thousands of miles. But 
this knowledge is far too vague. So we will 
make a still further approximation. Find a level 



74 THIRD LECTURE. 

region, and then measure due north or south on 
it till y du have changed your latitude one degree^ 
This measure multiplied by three hundred and 
sixty gives you the true circumference of the 
earth, supposing that circumference to be strictly 
circular. The result is about twenty-five thou- 
sand miles. This is a close approximation ; for, 
after all, the earth differs but very little from 
a perfect sphere. Still astronomers are not con- 
tent. They know the body is not an exact 
sphere. They have a sort of constitutional weak- 
ness for the last degree of accuracy — they must 
hunt down, if possible, the ten-thousandth part 
of a mile in favor of both equatorial and po- 
lar diameter. And, indeed, it was a matter of 
such great practical consequence to know these 
elements with minute precision that Governments 
stepped in with their vast resources to help mea- 
sure them. Coalitions in behalf of the balance 
of power became, for the time, coalitions in behalf 
of astronomy. For the time, jealous and hostile 
powers resolved themselves into a Committee of 
the Whole on the diameter of the earth. Nations 
took stock in degrees of latitude as people lately 
did in petroleum. " Select your men and instru- 
ments," said some six or eight Governments to 
men of science, " and we will pay. expenses." So 
the work was put into choicest hands ; the choicest 
instruments were gathered ; and the illustrious 
laborers hent themselves to their task with the 



SHAPES AND SIZES OF THE TWO BODIES. 75 

determination to spare neither time, nor pains, 
nor expense, to secure the most reliable results. 
Their object was the same as in the case just sup- 
posed. It was to measure lines running due 
north or south on the earth — only they would 
measure very long lines, very many of them, and 
in as widely differing latitudes as possible. Thus 
they would get a choice average length of a de- 
gree of latitude, and also settle with great preci- 
sion its rate of increase as we go from the equator 
toward the poles. But it is hard to find level dis- 
tricts of great length on due north and south 
lines. So they determined to follow the level re- 
gions in whatever direction they ran, and indeed, 
on occasion, forsake them altogether ; and after- 
ward reduce their zigzag measurements to the 
meridian and sea-level, by means of triangles and 
levels. And so they did. They wove a network 
of triangles across large tracts of country in vari- 
ous parts of the world. They went stooping 
along the dead plains, chain in hand, for their 
base lines ; they went spying from hill-top to hill- 
top, and from beacon to beacon, with their theod- 
olites and circles — as our own Coast Survey 
Commission were seen doing in this neighborhood 
some years ago, and as they have been doing on 
other parts of our mighty coast as fast as the 
mighty war would suffer them. International 
triangles united countries as international rail- 
roads do now. Let France hold up this angle, 



76 THIRD LECTURE. 

Spain that, Italy the other ! No climate was too 
h )t, none too cold, for these zealous workers. Trig- 
onometries could stand any climate — why should 
not Clairaut and Godin ? So forward, ye pil- 
grim geometers ! Spread out your triangles 
along the plains ! Hang them from the tops of 
mountains ! Float them along the seas ! Stretch 
them across the sands of the desert! Shadow 
them with jungles and palms, and blister them 
with vertical suns ! Anchor them to icebergs, and 
bury them in eternal snows ! And so they hardi- 
ly and audaciously did. A line of 16° of latitude 
was measured in India, of 12° in France, of 4° in 
England, of 3° in Russia, of 3° in Peru, of 2° in 
Italy, of 1° each in Sweden, Lapland, Africa, Unit- 
ed States — indeed, twenty independent measure- 
ments in all. The results obtained from a com- 
bination of these were 7,925.648 miles for the 
equatorial diameter, and 7,899.170 for the polar. 
The old magicians drew circles ; these new ma- 
gicians drew triangles. The former were sup- 
posed to get wondrous results out of their figures, 
drawn with many a muttered hard word and 
strange gesture — what will these philosophers 
get with their words as hard, and pointings as 
mysterious, and figures as uncouth? Nothing, 
my friend, nothing but the diameter of the earth 
in good British statute miles and thousandths of 
a mile — which, however, happens to be worth 
mor° than all the work done by all the magicians, 



MUTUAL GRAVITATIONS. 77 

astrologers, and soothsayers, from the days of Be- 
rosus downward. 

The moon can not boast such great dimensions 
as the earth. Still it is wonderfully larger than 
it looks. It looks, say, a foot in diameter ; it 
really is eleven million times that. It is plain that 
can not be a small body which, on being carried 
away from us 240,000 miles, appears as large as 
the moon. But this is altogether too vague in- 
formation to content astronomers — astronomers 
who want to split a second into one thousand 
parts, and an inch into 200,000. " What is the 
exact length of the diameter in miles and small- 
est possible fractions of a mile ? " demand they. 
And they answer themselves in this way. Sup- 
pose two lines drawn from the earth's center to 
opposite sides of the moon ; then the real diame- 
ter of the moon makes with these a triangle. 
Now measure the moon's apparent diameter, 
which is the angle included between the supposed 
lines. The lines are about 240,000 miles each ; 
the angle is about 31'. Then the simplest sort 
of mathematics gives you two thousand one 
hundred and sixty miles for the required diam- 
eter. 

Though the moon is so small a body compared 
with the earth, and withal so remote from us, it is 
able to produce on us some very remarkable effects. 
Most certainly I do not here refer to its supposed 
bearing en the weather, on the complexion, on 



78 THIRD LECTURE. 

the health, on the mind in producing or modify- 
ing insanity, on the proper times for planting, 
reaping, felling timber, killing of domestic ani- 
mals. Though the impression was once almost 
universal, and is still exceedingly prevalent, that 
the moon is a powerful and controlling agent in 
these and such particulars, still we must admit 
that it is an altogether erroneous impression. 
This has been very satisfactorily established by 
the extended observations and experiments of 
several European philosophers, and especially of 
the illustrious Arago. No : I refer to quite a dif- 
ferent class of phenomena. And, first, the moon 
takes hold of that protuberant equator of ours, 
as if it were a mere convenience for wrestling, 
and pulls and twists it about after itself, making 
the pole describe a wavy, nodding circle of some 
46° diameter through the sky — a little more than 
the hight of the North Star above our horizon. 
This effect is due partly to the sun ; but the moon 
is the chief agent. For long periods, however, 
this motion of the pole would not be noticed by 
common observers ; it is so exceedingly slow, 
requiring about twenty-six thousand years to 
make an entire revolution. In consequence of 
it, the axis of the earth which now points nearly 
at the North Star, will, after pointing a little 
nearer to it, gradually recede, and twelve thou- 
sand years hence point 40° away from it ; and 
then the bright star Lyra will be the pole-star. 



MUTUAL GRAVITATIONS. 79 

Let the men of the year 13,860 look in the north- 
west for their north. 

Another more noticeable effect of the moon's 
attraction are the tides. Twice a day the earth, 
like every good man, attempts communion with 
the sky. Twice a day the bosom of the seas swells 
heavenward. The explanation is this. As the 
earth, in revolving on its axis, presents all parts 
of its surface in succession to the moon, that 
body, by the attraction of gravitation, draws up 
the water in a ridge toward itself, at the same 
time making a similar ridge by drawing the earth 
away from the water on the opposite side : so that 
we have two great tidal swells, convex toward the 
west, about twelve hours apart, apparently follow- 
ing the moon in its daily movement around the 
earth ; checked somewhat in their movement by 
their own inertia and friction among the barriers 
of shores and irregularities of sea-beds ; re- 
flected in this direction and that, according to the 
lay and shape of coasts ; about two and a half 
feet high on the average, but heaped up as high as 
fifty or even one hundred and twenty feet in 
some confined places of peculiar conformation, 
and then almost or quite dissipated by shoals and 
other dispersive agencies. Thus it would seem 
to a bird's-eye view. But really there is no pro- 
gressive movement of the water in the open sea 
in the case of the tides. No European water is 
rolled over to America at the rate of a thou- 



80 THIRD LECTURE. 

sand miles an hour. It is merely a successive 
rising and sinking of the sea all round the world. 
The effect is owing in part to the attraction of the 
sun ; but the moon is the chief agent. When the 
sun and moon act in the same line, or nearly so, 
— at the times of new and full moon — the tide- 
swell is considerably increased, making what 
are called spring tides. When they act at right 
angles to each other, they impair each other's in- 
fluence and the tide-swell is decreased, making 
what are called neap tides. 

This constant heaving of the water tends to 
keep it pure. It also agitates to some extent the 
atmosphere, and so keeps that in a livelier and 
purer state. It enables all the coasts of the world 
to become vast beds of a peculiar animal and ve- 
getable life, and twice a day throws open the re- 
positories to the plundering hands of men. The 
farmer wants his sea-weed and salt grass. All 
persons, almost, want their shell-fish. Millions 
of people find their chief support in those vast 
tribes of animals that can only live where tides 
are felt. Shoals are laid bare and quickened by 
the sun. The tide-wave brings up the water 
again with its flotilla of semi-marine animals and 
influences to impregnate and refresh the conge- 
nial sand or slime. So the beach swarms. Races 
of creatures belonging to both land and sea, and 
partaking of the qualities of both, present them- 
selves for our tables in countless numbers — not 



MASSES AND DENSITIES. 81 

by spontaneous generation, that figment of athe- 
ists, but by the good providence and almighty 
power of God^ 

How much matter is contained in the earth ? 
What is its average degree of compactness ? In 
the year 1774 — the same year we Americans 
were weighing the maternity of England in the 
balance and finding it wanting — England at- 
tempted to weigh the world. For that purpose, 
the astronomer royal, Dr. Maskelyne, betook him- 
self to Schehallien, in Scotland. He suspended 
a plumb-line near the mountain, and noticed how 
much it was drawn out of the perpendicular. 
This showed what proportion the quantity of 
matter in the mountain bore to that in the earth. 
Then cuts into the mountain in every direction 
were made to show the average density of the 
materials of which it was composed. With this, 
the size of the earth being known, it was very 
easy to arrive at its average density — which was 
found to be about five and a half times that of 
water. This greatly exceeds the density of the 
surface. So there must be a great increase of 
condensation toward the center. It does not fol- 
low, however, that the earth is perfectly solid, 
— the contrary is known — only the parts that are 
solid must be exceedingly so ; fit walls against 
those tremendous internal fires that help the sun 
defend us from the tremendous cold of space*; 
fit walls against the noxious gases and vapor 



82 THIRD LECTURE. 

which those fires can not fail to generate in pro- 
digious amount ! For the earth is like some men 
— with a cold exterior, but a heart of fire. It is 
a traveling furnace. Wherever we dig into it, 
we find a steady increase of heat — one degree for 
each fifty-four feet as we descend. And you know 
how unlike are the climates of different countries 
having the same latitude and level — for exam- 
ple, Southern Europe and New England and the 
States due west of us. When the ancients saw 
iEtna in eruption, they supposed the mountain to 
be the chimney to the great blazing and resound- 
ing forges below, where Vulcan the god-black- 
smith, with his journeymen-Cyclops, were ham- 
mering out the thunderbolts of Jupiter. When 
we see iEtna and its three hundred sister volca- 
noes, in all parts of the world, in action, we make 
no question but that the immense roaring fires 
are beneath them, if not the forger and the 
smiths and the thunderbolts. That the great 
amount of vapor and gases which must be de- 
veloped by these fire-beds does not all escape 
through fissures and volcanoes as fast as formed, 
is plain ; for the many violent and far-spreading 
earthquakes that occur, come from the struggles 
of imprisoned elements to escape. They are 
densely accumulated in great caverns. And it is 
well that the walls of these caverns are denser 
than the densest metals known to us, so that 
but comparatively little of the deadly air within 



MASSES AND DENSITIES. 83 

succeeds in escaping to the s irface. Indeed, so 
little heat escapes that the earth has not dimin- 
ished its mean temperature by the three-hun- 
dredth part of a degree for two thousand years. 

Can we also weigh the moon in our astronomi- 
cal balance ? We can ; by means of the tides. 
Add together the average spring and neap tides 
— the one expressing the sum, and the other the 
difference, of the solar and lunar attractions. This 
gives us that part of the tide-wave which is due 
to the moon alone. Now how does this show the 
quantity of matter in the moon ? You see it is 
a case of contest between the earth and moon as 
to which shall have the water. The earth pulls 
with all its might — that is to say, with all its quan- 
tity of matter ; and the moon pulls with all its 
might — that is, with all its quantity of matter. 
The moon acts at disadvantage from its greater 
distance, the earth acts at disadvantage from 
the tendency to fly off which the water has in con- 
sequence of rotation ; but, when allowance is 
made for these things, the position which the 
water takes between the two pulling bodies shows 
their relative strength. It is the case of Greece 
and Troy dragging at the body of Patroclus. 
The one tugs at the head, and the other at the 
feet ; the direction in which the body actually 
goes shows which party is the stronger, and the 
rate at which it goes shows how great the superi- 
ority is. At last the dead hero moves swiftly 



84 THIRD LECTURE. 

toward the ships. Not eighty wrestlLg Troys 
could prevent it. In this duel for the seas, we 
are Telamonian Ajax, and the will of Jupiter 
besides ; and it would require more than eighty 
moons to turn the fortunes of the day, and tear 
its prize from the stalwart earth. Just as soon 
as we know the relative quantity of matter in the 
moon, its known size shows what is its relative 
density. It is about three-fifths of the density of 
the earth. 

It has been shown that the earth and moon, 
making as they do a neighborhood by themselves, 
must revolve about their center of gravity. Now, 
since the earth contains eighty times as much 
matter as the moon, this center must lie eighty 
times nearer to the center of the earth than to 
that of the moon. But the eightieth part of two 
hundred and forty thousand miles is three thou- 
sand. So you see that the point around which 
the two bodies revolve falls one thousand miles 
within the earth's surface — our semi-diameter 
being near four thousand. Hence it is compara- 
tively but a very small orbit that the earth de- 
scribes — only six thousand miles across ; while 
the moon describes one which is four hundred and 
eighty thousand miles across. One is as nothing 
to the other. So, for popular purposes, it isccm- 
mon to consider the earth as stationary, so far as 
the moon is concerned, with the moon revolving 
around it. Turning, then, to this greater orbit, 



ORBITS. 85 

I will state some of the more interesting facts 
about it. Plainly, it can not differ much from a 
circular curve ; for the moon always looks just 
about so large during its revolution around us. 
If its distance from us varies considerably, of 
course its apparent size ought also to vary consid- 
erably. Very nice measurements, however, of its 
apparent diameter at different times, show that 
its distance does alter somewhat — more than it 
ought on account of our being a little out of its 
center of motion ; shows in fact that the orbit 
must be what is called an ellipse — such a figure 
as a flexible hoop would make if compressed at 
opposite sides — having the common center of 
gravity about twelve thousand miles one side of 
its center, on the longer axis. It takes a little 
more than twenty-seven days for the moon to 
make the complete circuit of this orbit. This is 
traveling at the rate of fifty-four thousand miles 
a day. In passing around this orbit, our satellite 
often passes, either wholly or partially, through 
the earth's shadow ; giving rise to lunar eclipses. 
As to the position of the orbit, we notice that the 
moon does not move around our axis at right 
angles to it, but obliquely ; so that the plane of 
the orbit makes an angle of about sixty degrees, 
with the axis. This inclination is of great ser- 
vice to us ; for it is owing to this that we have so 
much more light from the moon in winter than 
in summer ; it causing the full moon to ride 



86 THIRD LECTURE. 

highest when we need the most light. Here, 
then, we have the orbit — four hundred and 
eighty thousand miles the longest way across, 
lying obliquely across the axis of the earth, and 
traversed at a pace of fifty-four thousand miles 
a day. This is how the matter stands now. But 
you are not to suppose that it has always been so, 
or that it will always be so. The orbit is contin- 
ually becoming smaller ; the moon with every revo- 
lution is getting nearer and going faster ; and 
some persons have been afraid that, at last, our 
neighbor would become too neighborly — in fact, 
come rushing in upon us, and with one tremen- 
dous concussion dash every thing to pieces. The 
fact of the gradual approach of the moon to us 
is certain ; observations establish it beyond ques- 
tion. But it is an exceedingly slow approach, 
only ten seconds on the time of revolution being 
now gained in a century. Still, however safe we 
and many generations after us may be, the idea of 
such an ending of an astronomical system is not 
pleasant. We pity that distant generation to 
come. We pity the graves of our fathers and 
our own. However, we need not be alarmed. 
La Place, with his splendid geometry, has shown 
from the doctrine of gravity that this gradual 
contraction of the orbit is not to continue indefi- 
nitely ; but that, after millions of years, it will 
again slowly expand and finally become as large 
as ever ; then contract again — and so sweep back- 



MUTUAL ASPECTS. 87 

ward and forward through a period the vastness 
of which bewilders the imagination. T His change 
in the lunar orbit is by no means the only one. 
There are some sixty such changes ; and about 
half that number are so considerable that they 
must be taken account of, whenever we wish to 
compute the place of the moon with tolerable ex- 
actness. Indeed, the moon's orbit is a very wavy, 
changeable, battered affair. It is continually be- 
ing pushed out and in, twisted in this direction 
and in that, drawn sidewise and edgewise, re- 
volved in its own plane and in almost every other 
by attractions from many quarters. Could you 
see the path which our satellite actually de- 
scribes in space — could it leave a visible wake 
as a rocket does — you would wonder greatly at 
its intricacy, and how men could ever get able to 
predict the moon's place on it to within live sec- 
onds of the truth. Yet this they can do. And 
astronomers have found out, by means of the law 
of gravity and that wonderful differential and 
integral calculus which is the good Genius of 
astronomy, that, notwithstanding the sad usage 
which the lunar orbit gets from all quarters, 
it has, like much assailed christian goodness, 
within and around it all the elements of eternal 
stability. 

I will close my account of our satellite system 
by a few words as to the appearance which its 
members present to each other. 



88 THIRD LECTURE 

The appearance of the moon under the teles* 
cope is very beautiful. And yet it looks very 
much as if it had had the small-pox in the natu- 
ral way, and had it sadly. We see a desperately 
pitted and scarred face — valleys and mountains 
— valleys four miles deep ; mountains five miles 
high ; volcanoes, conical, ring-shaped, with long 
streams of lava spreading down their sides in 
every direction; peaks gleaming with the first kiss 
of the morning sun ; shadows advancing across 
the plains. As to atmosphere and water on the 
moon, appearances are indecisive. Some things 
seem to prove their presence, and other things 
seem as strongly to prove their absence. Cer- 
tainly the moon has never any clouds. However, 
if it could be demonstrated that it has neither air 
nor water, it would not follow that it has no in- 
habitants. It would only follow that, if there are 
living beings there, they must be differently con- 
stituted from ourselves. And who will undertake 
to show that beings widely diverse from us are 
impossible or improbable in the universe of so 
versatile and magnificent a Creator as He who 
spake into being these wonderful worlds of as- 
tronomy ? 

This is how the moon looks from the earth. 
A.nd how does the earth look from the moon, if 
there are people there to see ? Half of the moon 
never sees us at all. To the other half we seem 
a brilliant orb about thirteen times larger than the 



MUTUAL ASPECTS. 89 

moon seems to us — always occupying nearly the 
same place in the sky — successively crescent, gib- 
bous, and full — in fact, another moon. Under a 
telescope, what with our clouds and seas and val- 
leys and mountains, the earth would present even 
a more pocked aspect than the moon does to us. 
Never did veteran come home from the war with 
half so scarred and battered a countenance ! But 
never mind, ancient earth ! Thou hast a better 
look on closer acquaintance. And, besides, " hand- 
some is that handsome does," and thou gener- 
ously givest us flowers and fruits and harvests 
and coal and silver and gold and gems ; green 
fields, stately forests, musical streams ; sweet 
vales of Tempe, hoary Alps sublime, august 
oceans with their eternal anthems ; above all, a 
standing place on which Holy Christ and sinful 
we may work out for ourselves the wonders of 
eternal life. 



IV. 
PLANET SYSTEMS. 



91 



IV. Planet Systems. 

Example — Solar System. 

i. ORDER OF BODIES 93 

2. PERIODS 103 

3. DISTANCES FROM SUN 105 

4. SHAPES AND INCLINATIONS OF ORBITS . . .111 

5. SIZES 115 

6. VELOCITIES 117 

7. MASSES AND DENSITIES 118 

8 PERTURBATIONS . tso 



FOURTH LECTURE. 



PLANET SYSTEMS. 

IN my last lecture I gave an example of the 
First Order of Systems among the heavenly 
bodies — the Satellite Systems. This evening I 
propose to give an example of the Second Order 
— the Planet Systems, or systems each of which 
is composed wholly or in part of Satellite Systems 
revolving about a self-luminous body or sun. 

The rotation of the earth makes all the heav- 
enly bodies seem to move across the sky in parallel 
lines, without any disturbance of their mutual po- 
sitions. But some of these bodies have very much 
motion of another kind — a motion among them- 
selves. They go this way, and they go that ; they 
go forward, and they go backward — describing 
quite rapidly very irregular paths on the sky. I 
have already called your attention to these very 
roving bodies, under the names of planets and com- 
ets. About ninety planets, and some one hundred 
and eighty comets, have been carefully noticed. 

93 



94 FOURTH LECTURE. 

Some of these change their places among the other 
stars, on the average, as much as eight times the ap- 
parent diameter of the sun in a single day — indeed 
some comets have been known to traverse, in the 
same time, eighty times this diameter. Besides 
these, the sun itself is found to be a great traveler, 
though never a retrograde one — making the 
whole circuit of the heavens in a year. Now, the 
thing to be particularly noted, is the great differ- 
ence in amount between the apparent motions of 
these bodies and the apparent motions of all others. 
Why, all others have no motions at all, that ordi- 
nary observers can detect, and hence are called 
fixed stars. And when astronomers mount their 
instruments, and do succeed in detecting small an- 
nual changes of place among them, they find that 
the greatest of these changes is a thousand times 
less than that of the slowest planet. Now what 
makes this great chasm ? Why do these three hun- 
dred bodies seem to move so much, while all the 
rest seem to move so little ? There is but one an- 
swer. Those greatly moving bodies are- greatly 
nearer to us than are the others. There is a great 
interval between the two classes of bodies in space, 
corresponding to the interval between them in mo- 
tion. If there were no space-chasm between them, 
the law of gravity would require them all to belong 
to the same system of revolution ; of course, the 
real motions, and so the apparent, of all would be 
of the same general order of magnitude. Suppose 



ORDER OF BODIES. 95 

yourselves at sea in a fleet. Here are three hundred 
ships within two miles of you. Some are standing 
this way and some that, some advancing and some 
retrograding ; but all noticeably changing their 
positions with respect to you and each other every 
minute. Now let another fleet appear on the hori- 
zon. You count a thousand tiny masts. Their 
progress seems as petty as their size, hours scarcely 
showing any change of position. What say you v 
That those Liliput ships with their Liliput mo 
tions are mingled with your own squadron, be- 
cause, forsooth, you happen to see them between 
the neighboring hulls and masts ? Not so. If 
they belonged to you, they would take signals 
from your flag-ship, and all the exuberant ship- 
ping in sight would have a family likeness as to 
the character and degree of their sailing. But here 
is quite another order of motions. They plainly 
belong to another fleet, under another admiral, 
far away in the offing ; and distance has dwarfed 
both figure and motion. A great breadth of sea 
lies between the two navies. We reason in the 
same way in regard to the heavenly bodies. 
These three hundred bodies, more or less, that 
show so much motion, we conclude to belong to 
our fleet of stars ; the others that scarcely stir on 
the sight belong to other fleets or fleet, separated 
from ours by a wide interval. The three hundred 
and the earth are astronomical neighbors. The 
three hundrei and the earth are a system by 



96 IOUBTH LECTURE. 

themselves — if you please, an astror. onrical Leon- 
idas and his Spartans, keeping ward at the Ther- 
mopylae of the sky, and endeavoring to beat off 
the crowd of Chaldean astronomers that seek to 
reach the very heart of the heavens. They can 
not be beaten off. By dint of numbers and pa- 
tience, if not of boldness and genius, they shall 
break through. The very heart of that Greece 
shall be laid open. 

According to the law of gravity, all the mem- 
bers of this system must be in a course of revo- 
lution about their common center of gravity. 
Where is this common center ? It may be an in- 
visible point out in the void of space, far away 
from any member of the system ; and again, as in 
the case of the earth and moon, it may lie near 
the center of some body. The ancients always 
assumed the last supposition to be the true one ; 
and further assumed that the earth is that central 
body about which, not only the sun and planets 
and comets, but all the huge varieties of nature 
revolve. Themselves were the center of creation. 
It is something in their favor that they did not 
know how large creation was. But the children 
are wiser than the sires. Since the time of Co- 
pernicus — that astronomical Columbus — men have 
seen reason to change their opinions on a great 
many subjects ; on this among the rest. Now 
we know that the sun occupies nearly the center 
of motion of that system of planets and comets 



ORDER OF BODIES. 97 

to which we belong. This should have been sus- 
pected from the beginning — especially in view of 
the desirableness of having the only self-luminous 
body in the system placed somewhere near its 
center. And the suspicion should have been 
easily turned into a conviction. Suppose the 
earth to be practically at the center of motion. 
Then all the planets and comets would seem to 
describe, in a course of perpetual progress, regular 
circles about us ; whereas they all, without ex- 
ception, advance and retreat on most irregular 
curves. So the earth can not be the center. 
Next, suppose one of the other members of the 
system to be it. Then that central body, being 
the center of our motion, would appear to describe 
in unbroken progress a regular circle among the 
fixed stars. Now the sun is the only body in the 
system which fulfills this condition. Its apparent 
path is a regular circle ; described in one year, 
without any retrogradations whatever ; while, as 
I have said, every other member of the system 
apparently moves on a very irregular line — now 
forward, now backward, now side wise, now stop- 
ping altogether — in short the picture of irresolu- 
tion. More eccentric vagrants than those planets 
and comets seem to be, it would be hard to find. 
But the sun marches steadily along. He seems 
to know what he wants and the way to it. Right 
forward on the periphery of a great circle, with- 
out a step to the right hand 01 to the left, he 

7 



98 FOURTH LECTURE. 

presses, till he comes around to the same fixed 
star again. So the sun is practically the center 
of the system. It is the sun, and not the earth, 
who is the patriarch of yonder seemingly wayward 
and disorderly family, and who — shall we say it 
— is responsible for this misbehavior. But things 
are not what they seem. There is nothing dis- 
orderly in the universe save intelligent beings. 
Could we stand at the sun, the motion-center of 
all these graceless nomads of the sky, they would 
no longer seem so indictable for vagrancy and in- 
subordination. All their zigzags would be straight- 
ened out, all their stops and retreats would be 
turned into one constant advance. See how much 
depends on having the right stand-point for view- 
ing things ! And the wisdom of the Great Architect 
of astronomical systems is saved from aspersion 
as we see the chief source of light and heat in our 
stellar community so placed as to be of the great- 
est service to the greatest number — so placed as 
to oppose, as much as possible, extreme variations 
of illumination and temperature on any world. 

But now what are these bodies thus revolving 
about the sun ? First, we have the earth and 
moon — one satellite system. Next, take a tele- 
scope — a common spy-glass will answer — and 
bring it to bear on the planet Jupiter. You see 
a well-defined disc, and four bright points in its 
immediate neighborhood. Watch, and you shall 
notice these bright points approaching the planet, 



ORDER OF BODIES. 99 

crossing its face, going a little beyond it, then 
coming back to it, disappearing behind it, after a 
while appearing on the opposite side, and then re- 
ceding from it as far as before ; watch them, and 
you shall find them keeping with the planet in all 
its wanderings among the stars, advancing when 
it advances, retreating as it retreats, becoming 
stationary relatively to other stars when it becomes 
stationary. Plainly, another satellite system — 
a reflecting primary, with four moons waiting upon 
and revolving around it. There is the planet 
Saturn ! Look at it with a more powerful glass, 
and see — what you shall see. If your eyes are 
good and your telescope is of the first class, you 
will by patient watching be able to detect eight 
bright atoms in the neighborhood of a curiously 
beringed disc, behaving toward it just as the 
satellites of Jupiter do toward their primary. 
Plainly Janissaries ; plainly, another satellite sys- 
tem — a reflecting primary, with eight moons re- 
volving around it. — Hunt up the planet Uranus, 
never visible to the naked eye, but seen well 
enough with an instrument ; and, if you manage 
your instrument as well as Sir W. Herschel and 
his sister did theirs, eighty-four years ago, you will 
see that reflecting disc moving about with what is 
evidently its body-guard of six moons. Another 
satellite system ! — So of Neptune — a newly-dis- 
covered planet. Hunt patiently in its close neigh- 
borhood;, as it shines in the field of a powerful 



100 FOURTH LECTURE. 

telescope, and, if you do as well as Struve did at 
Pulkova, and Bond at Cambridge, you will find at 
least one minute point of light playing the hench- 
man to his chief. Another satellite system! 
Thus it appears that we have a great system of 
heavenly bodies, composed largely at least of 
satellite systems revolving about the sun. No 
satellites have as yet been discovered in connection 
with other planets. This discovery, however, may 
yet be made. One has been suspected waiting 
on beautiful Venus. In short, we have an ex- 
ample of a stellar system of the second order. 
We have a Planet System. We have a number 
of heavenly sires with their comely families of 
various sizes about them, still bound in invisible 
bonds to, and in course of circulation around, the 
ancient and majestic grandsire — whose eye, how- 
ever, is not yet dim, nor natural force abated. 

Having thus found our Planet System, let us 
proceed to consider its chief points of interest. 
And, first, the order of the bodies composing it. 
Suppose one to start from the sun and travel to the 
frontiers. What body would he reach first, what 
secondly, and so on ; supposing them all ranged 
on the same side of the sun, at their average dis- 
tances ? At first glance it looks a hard matter to 
answer these questions. The members of the 
system seem quite too insubordinate to adhere to 
any order of position and revolution that may 
have been assigned to them. Here, is one refrac- 



ORDER OF BODIES. 101 

tory planet with its strange path ; there, a still 
more refractory comet with its stranger ; one is 
going this way, another that ; one is creeping 
northward, another striding westward — in short, 
it is a perfect maze of positions, directions, and 
motions that we see. But there is a clew to the 
labyrinth. There is a key to this sky-cipher and 
hieroglyphic. And it is something that does not 
look particularly like a key at first sight, though 
it can be made, in connection with the law of 
gravity, to interpret, not only the order, but also 
the periods and distances from the sun of all the 
members of our system. This Rosetta stone is 
the average apparent daily motions, which any one, 
almost without instrument but with a plenty of pa- 
tience, could approximately determine for him- 
self; and which, with such instruments as every 
observatory is now furnished with, can be deter- 
mined with admirable exactness. A word as to 
the general method. The law of gravity proves 
that the more remote a revolving body is from 
its center of revolution, the more slowly it must 
move ; and, of course, the more slowly it must 
seem to move, as seen from that center. Hence, 
if we can only find how the motions of the planets 
and comets, as seen from the sun, compare with 
each other, we shall know their relative distances 
from that body. Now this is easily done. We 
have merely to find what their average motions 
are as seen from the earth. As we are nearer 



102 FOURTH LECTURE. 

to each by a whole diameter of the earth's oririt 
at one time than at another, taking the average 
reduces the motion to what it would appear mid- 
way between opposite sides of the orbit. Well, 
being thus reduced, how do the motions compare 
with each other ? For the planets, they decrease 
in the following order : Mercury, Venus, Earth, 
Mars, some eighty small bodies called asteroids 
or planetoids as you may prefer, Jupiter, Saturn, 
Uranus, Neptune. This then is the order in which 
these several planets would be reached by one 
going outward from the sun, could they all be ar- 
ranged on the same side of that luminary at their 
average distances. Comets would be encountered 
in great numbers all along the glittering journey 
— the best known of them in the following order ; 
Encke's, Biela's, Halley's, comet of 1811, comet 
of 1680. 

Such are the various places which his glittering 
nobles hold in that great court which the solar 
monarch maintains in the sky. Mercury holds 
the place of honor ; he waits perpetually in pres- 
ence. Neptune is a mere hanger-on at court — 
getting comparatively few rays of favor, and 
obliged to content himself with exceedingly dis- 
tant and dim views of his sovereign. The earth 
has a golden mean of position — not a Steenie, in 
the dangerous post of a favorite putting up at the 
palace — not a governor-general of Van Dieman's 
Land and all British Antipodes — but Duke 



PERIODS OF PLANETS. 103 

Percy, living in an independent way o a his estates 
in Northumberland, in a very genial temperature 
of court favor, neither loved too much nor too 
little, always welcome and never wanted, far 
enough from St. James's and not too far. 

How long are the members of our system in 
traveling around the sun ? The average daily 
motion, as seen from the sun, answers this ques- 
tion also. For if you find this motion to be — say 
1° — you know that it will take three hundred and 
sixty days for the planet to accomplish the whole 
circumference of the heavens. If Mercury moves 
around the sun at a mean daily rate of 4° 5', as 
it does, it will take it eighty-eight days to go 360°, 
or an entire circuit. And so on. In this way we 
find the period of Mercury to be three months, 
of Venus seven months, of the Earth one 
year, of Mars two years, of Jupiter twelve, of 
Saturn twenty-niue, of Uranus eighty-four, of 
Neptune one hundred and sixty-four. Ask that 
man of silver hairs how old he is. Eighty-four 
years, does he say ? Then he was born when 
Uranus was last at its present point in its orbit 
— the point where Sir William Herschel was 
then finding it. The child, whose fresh, dewy orbs 
to-day look up wonderingly at the spangled vault 
where Neptune hides itself, will have grown up, 
fought life's battle, grown old, died, and lain in 
his grave a hundred years, by the time that fron- 
tier planet is able to get around again to its pres- 



104 FOURTH LECTURE. 

ent place m the sky ! According to the Neptunian 
calendar, it is only thirty-six years since the cre- 
ation of Adam ! But even such years are trifling 
when compared with those of some comets. What 
think you of a voyage about the sun requiring 
four thousand of our years for its completion ? 
The comet of 1811, when it last saw the earth, 
saw it yet dripping with the waters of the flood ; 
the comet of 1680, when it last saw the earth, 
saw it without form and void, and prophesying 
but faintly of an Eden and an Adam still three 
thousand years distant. When it sees the earth 
again, where shall we be — ourselves, our homes, 
our cities, our race ? May Heaven grant that the 
next nine thousand years shall suffice to prepare for 
exhibition to the gaze of that mighty voyager, the 
predicted new heavens and new earth in which 
shall dwell righteousness ! 

Having the periods of the members of our sys- 
tem, and the actual distance of one of them from 
the sun, we can find the distances of all the rest. 
For the mathematics of Newton have proved, that, 
in case the central body of a system is greatly 
superior in mass to the sum of all the others, it 
follows from the law of gravity that the squares 
of the periods of any two of them are as the 
cubes of their mean distances from the center. 
That this condition is fulfilled in the case of our 
own system is clear ; for all observation shows 
that the sun, relatively to the planets and comets, 



DISTANCES FROM THE SUN. 105 

is substantially at rest. Hence the law which 
Newton proved is applicable to our system — the 
squares of the periodic times are as the cubes of 
the mean distances from the sun. By the help of 
this law and the periods, if we can find the mean 
distance of one planet from the sun, we can find 
the mean distances of all the planets. Let us then 
find the distance of the earth from the sun, as a 
means to that of every other member of the 
system whose period is known. 

One very easy way of approximating to our 
distance from the sun was employed by the an- 
cients. Sometimes a half-moon is visible during 
the day. At such a time let a line be drawn from 
the center of the sun to that of the moon, thence 
another line to the center of the earth, thence 
another back to the center of the sun — making 
a right-angled triangle. Now let us measure the 
angular distance of the moon from the sun. 
This, with the known distance of the moon from 
the earth, enables us ^o find with the greatest ease 
that other side of 'ne triangle which is the dis- 
tance between the centers of the sui/ and earth. 
But this is only a rough approximation In these 
times astronomers would curl the lir* at such 
coarse measurements as these. Why, then, not 
find our distance from the sun in the same way 
we did our distance from the moon — that is, by 
noticing how much the sun is apparently dis- 
placed on the sky by a givni change in our place 



106 FOURTH LECTURE. 

on the earth — that is to say, by its parallax ? 
This will do : only, on account of the exceeding 
smallness of the solar parallax, we can lot employ 
the same method for determining it as was used 
in the case of the moon. A very accurate method, 
however, was discovered by Dr. Halley, the 
friend of Newton, and bequeathed by him to the 
next generation of astronomers, to be used when 
fitting occasion should arrive. This was the 
method. Occasionally the planet Venus crosses 
the sun's disc. Now, if we can only find how 
much Venus is displaced on the disc at that 
time by our going a given distance on the earth, 
we can know how much the sun is displaced on 
the sky by the same change of place ; for the one 
displacement is to the other as the distance of 
Venus from the sun is to her distance from the 
earth. But this latter ratio is easily obtained 
from the average apparent daily motions of the 
two bodies, by means of that law connecting the 
periods and distances which has just been referred 
to. It is as 2J to 1. So, in 1769, the English, 
French, Russian, and other European Governments 
fitted out expeditions to observe, from as widely 
separated parts of the world as possible, the transit 
of Venus which occurred that year. One corps of 
observers went to Wardhus — a small island on the 
Coast of Lapland ; another corps was carried by the 
celebrated Captari Cook to Otaheite, now Tahiti, 
in the South Sea All possible means were used 



DISTANCES FROM THE SUN. 107 

to secure extreme- accuracy of result. It was un- 
derstood by all parties, that they were measuring 
a base line that would be used in determining all 
the other distances in our planetary system, and 
perhaps distances stretching across the void of 
space to where other isles of light, and archipela- 
goes of such isles, go swimming about other glow- 
ing continents in endless circumnavigations. So 
the science and art of the day did their very best. 
The extremest refinements, both of observation 
and theory, were brought to bear. Spider lines 
were split by the observer, and differentials by the 
mathematicians. The result was 8" 57 — about 
2 3 q- of the sun's apparent diameter, — for the mean 
change made in the sun's place by our passing 
from the surface to the center of the earth. From 
this, by simplest triangle-proportion, was found our 
mean distance from the sun — 95,298,260 miles. 
Taking this distance and the law expressing 
the relation between the distances and the periods, 
we come, by a simple proportion, to a knowledge 
of the average distances of all the principal bodies 
in our system. We find Mercury to be thirty- 
seven millions of miles from the sun, Venus 
sixty-eight millions, Mars one hundred and forty- 
five millions, Jupiter four hundred and ninety- 
five millions, Saturn nine hundred millions, 
Uranus eighteen hundred millions, Neptune two 
thousand eight hundred millions. Some of the 
comets have still greater mean distances. That 



108 FOURTH LECTURE. 

of the comet of 1811 is not far from twenty-two 
hundred, millions of miles ; while that of the 
comet of 1G80 astonishes us with the mighty 
stretch of forty-four thousand millions — sixteen 
times the solar distance of Xeptune ! 

You see that we have come to a new order of 
distances in our astronomy. The distances we 
have to deal with in our every-day life are such 
as we pass over in going to our fields, neighbors, 
schools, churches, markets, occasionally a neigh- 
boring city ; and hours and miles answer very 
well to express such movements. Next, we learn 
that the earth we live on is nearly eight thousand 
miles through — this lifts us to quite another 
plane of distances. Our common walks and rides 
are lost by the side of such mammoth lines. 
Then we learn that the moon is two hundred and 
forty thousand miles away. See another plane 
and order of distances still ! The word " miles " 
begins to empty itself of its meaning in such com- 
binations. But we go on to learn that the moon 
is at our very door as compared with other mem 
bers of our planet system — that the sun is four 
hundred times as remote ; Xeptune eleven thou- 
sand times ; while the comet of 1680, that Minis 
ter of Foreign Affairs to his Solar Majesty, buries 
itself in that tremendous Ultima Thule whose dis 
tance is one hundred and eighty thousand times 
that of the moon. Do you take the meaning of 
such enormous intervals ? Have miles any mean- 



DISTANCES FROM THE SUN. 109 

Ing left to them ? ' Does not the bight of this 
last plane of our astronomical arithmetic seem 
almost too dizzy and cloud-mixed to stand upon ? 
And, when you are told that a car, running ex- 
press from the sun to that frontier of this planetary 
system of ours, would not need to put on brakes 
for five hundred thousand years, do your concep- 
tions seem any the less dizzy and astounded ? In 
that great calculus which has done so much for 
astronomy we encounter infinitely small quanti- 
ties of different orders. The zeros of the first 
order are of no account as compared with finite 
quantities — zeros of the second order of no ac- 
count as compared with those of the first — zeros 
of the third of no account as compared with the 
second — and so on. In practical astronomy we 
have the other end of the scale — infinites instead 
of infinitesimals — successive orders of largeness 
and grandeur gradually ascending into the dizziest 
hights of sublimity, to each of which that below 
it is as nothing. 

On comparing among themselves the various 
distances of the members of our planetary system 
from the sun, certain interesting facts become ap- 
parent. At our distance that luminary appears — 
you know how large — and so bright that you can 
not look at it a single moment with unwounded 
eyes. The brightest flame disappears when held 
up between it and us. At our equator men get 
from its disc an average temperature of 70° or 



110 FOURTH LECTURE. 

80° Fahrenheit. Now, suppose our thoughts to 
le chariots, and let us travel off in them toward 
the sun. At the distance of Mercury, the sun 
would appear six times larger and brighter than 
it did on the earth, and must be that number of 
times hotter — other things being equal. What 
a summer-two o'clock in the afternoon the Mer- 
curians must have ! If the supposed planet 
Vulcan were real, the sun from it would appear 
fifty times as large and bright as it does at the 
earth ; and the mean heat at the most exposed 
parts of the planet would be more than 8000°. 
What a long thermometer, not to say incombus- 
tible, must the Vulcanians require ! Going on 
still, as we near the surface of the sun, it expands 
so as to fill a half-heaven with its disc, and the 
heat is now three hundred thousand times what 
we have been accustomed to on the earth. Had 
we not had the prudence to provido ourselves with 
a jerkin of the very best asbestos, were not our 
thought-chariot itself a salamander safe of the 
very best quality, our traveling would now be 
for ever ended. But, as it is, we are able to pass 
around the sun ; and then, speeding outward as 
only thought-chariots, fancy -driven, can — past 
belted Jupiter, past Saturn with its three won- 
drous rings — we stop not till we reach Neptune. 
Looking back, we see the sun dwindled to the size 
of Venus — nine hundred times less than we saw 
it from the earth, and nine hundred times as dim 



DISTANCES FROM THE SUN. Ill 

and cold ; and yet giving as much light as six 
hundred of our moons. And, if our courage 
does not fail us on these dim frontiers and with 
the thermometer already standing some 50,000° 
below zero — if it is not too much of a transition 
even for us, thought-pavilioned as we are, to pass, 
all in a single minute, from the immeasurable 
furnace of the sun to the immeasurable refriger- 
ator of the very pole of our planetary system — 
let us keep on one stage farther to where the sun 
appears a star of inappreciable diameter, and 
where, in the heart of eternal night and of infinite 
congelation multiplied by two hundred and fifty- 
six, cruises the last known picket of our planetary 
system, the comet of 1680. We can not deny 
that, if worlds thus situated are peopled, it must 
be with beings very differently constituted from 
ourselves. And what of that ? We will not be 
guilty of the unphilosophy of assuming that the 
Infinite Creator has made bat one pattern of liv- 
ing creatures, or that the patterns are not as 
various as the circumstances of the spheres which 
his almighty hand has shaped and sent whirling 
through the void. 

You notice that I have spoken of average dis- 
tances from the sun. I did this, because I did 
not wish to assume what is contrary to fact ; viz., 
that the orbits of the planets and comets are cir- 
cular. Instead of being circles, they are all ellip- 
ses. This does not follow from the law of gravity, 



112 FOURTH LECTURE. 

as some treatises on astronomy seem to intimate. 
No body revolves about another through force of 
gravity alone. Mere gravity would cause them 
to rush together on the same straight line. It 
takes both gravity and a projectile force across the 
direction of gravity to make a system of revolv- 
ing bodies. The nature of the curve described — 
whether a circle or one of those other sections of 
a cone which mathematicians call ellipses, parab- 
olas, 'and hyperbolas — depends on the relation 
which the attracting force bears in amount and 
direction to the projectile. Now, as we do not 
know what the force and direction were with 
which Deity launched the various members of our 
system into space, we are forced to rely on obser- 
vation to settle the nature of the curves they 
describe. Let us then observe. If the orbits 
were exact circles, the law of gravity would 
cause them to be traversed at a constant pace. 
The apparent daily motion of the same body, as 
seen from the sun, would be always the same. Is 
it so in the case of any member of the system ? 
In no single case, whether of comets or planets. 
In that of the earth, its apparent daily motion 
as seen from the sun — which is the same as that 
of the sun as seen from the earth — is observed to 
be quite unequal. It is also noticed that there is 
a variation in the apparent diameter of the sun 
in the course of the year ; showing that we are 
at greater d : stances from it at some times than at 



SHAPES AXD 7XCLIXATI0XS OF ORBITS 113 

others. So we both satisfy ourselves that our 
orbit is an ellipse, and can tell just how elliptical 
it is. To find the exact form of the other orbits, 
and their inclinations if any, to our own, we can 
manage thus. You know that, if Cuvier found a 
single bone of an animal, he could build up the 
whole creature and picture it to you in just 
the size and shape with which 'it walked the 
earth twenty thousand years ago. In a similar 
manner, astronomers can, from a small piece of 
an orbit, build up the entire thing for us just as 
it stands in nature ; give us its exact shape and 
size and bearing in space, in fact, a perfect fac- 
simile. Any piece that you can cut out of a 
given circle will not fit any other circle, or any 
other curve line whatever. Each kind of curve, 
and each specimen of a given curve, has its own 
law of curvature. The problem, then, is to get a 
true piece of each orbit — to find the single bone 
from which to reconstruct the mastodon. If you 
could only place yourself at the sun, and draw 
innumerable lines of known length to points oc- 
cupied successively by a planet, you could by con- 
necting the extremities of these lines get its real 
path. Xow this you can do, in effect, by finding 
its apparent daily motion, as seen from the earth, 
at two times sufficiently apart to give you a sen- 
sible difference between the motions ; also care- 
fully noting the amount and direction of the 
motion during the interval. These elements, re- 



114 FOURTH LECTURE. 

duced to what they would seem at the sun, have 
certain definite mathematical relations to the lines 
desired, by means of which they may be drawn to 
any extent, and so the astronomer maps down a 
section of the orbit just as it stands in nature. 
Thus standing, that bit of a curve has wrapped 
up in it all the characteristics of the entire orbit, 
and they may be pressed out of it by the hydraul- 
ic press of rigorous mathematics. You may press 
out of it the eccentricity, the inclination to our 
orbit, the place of intersection, the place of near- 
est approach to the sun. In this way we can find 
that all the planetary orbits are ellipses, differing 
but little from circles, and all — those of the aste- 
roids excepted — lying in nearly the same plane ; 
while the comets revolve on ellipses of great ec- 
centricity, which lie across the orbits of the planets 
and incline to them at all angles. In some few 
instances . the broken pieces of cometary orbits 
have seemed to belong to parabolas instead of 
ellipses ; but the observations were too rough to 
be reliable. If parabolas, the bodies traversing 
them, on going away from the sun, would never 
return. 

Observation shows that all the planets, and all 
their satellites, excepting those of Uranus, revolve 
in the same direction, from west to east. The 
comets are not at all particular about following 
this example. Having set up in business on a 
principle of eccentricity, each goes off about the 
Bun in the direction that pleases him. 



SIZES OF SUN AND PLANETS. 115 

How large are these astronomical neighbors 
and companions of ours — this sun, these planets, 
these comets, most of whom look so small ? Have 
we been spending our time in considering the 
order and periods and distances and orbits of 
what, after all, are scarcely more than rounded 
pebbles ? Having already found the size of the 
earth to be something considerable, we have a 
curiosity to see how it compares with that of our 
fellow-travelers about the sun, as well as with 
that of the monarch himself. Are we so much 
larger than them all that we can plume ourselves ; 
so much larger as to give color to the ancient 
notion that the axis of the earth is the axle of 
the universe ? The fact that the earth is not the 
center of the system discourages the idea.. Also 
these tremendous distances from us at which our 
Admiral Sun is anchored and his subalterns sail, 
taken in connection with the appreciable discs 
which most of them show in the field of the tele- 
scope, give us still further inkling that they must 
be bodies of extreme magnitude. But let us 
reduce the matter to figures. How large does 
the diameter of the sun appear to the eye ? So 
many minutes and seconds. What is its distance 
from us ? So many miles. With these data, a 
single proportion and a single triangle give 
885,680 miles for the real diameter — making a 
space within which might nearly be described the 
whole orbit of the moon. This makes our astron- 



116 FOURTH LECTURE. 

omical chief one and a half million times larger 
than ourselves. A very CaBsar and Charlemagne ! 
The process for those of the planets which 
have appreciable discs, as well as for all the 
comets, is the same ; only we have to reduce the 
apparent diameters at the earth to what they 
would be at the sun, in order to use the mean 
distances, which are always given from the center 
of the system. Thus we get the following real 
diameters, in round numbers : of Mercury, three 
thousand miles ; of Venus, eight thousand ; of 
Mars, four thousand ; of Jupiter, eighty-nine thou- 
sand ; of Saturn, seventy-nine thousand ; of Ura- 
nus, thirty-five thousand ; of Neptune, thirty-one 
thousand. As the asteroids have no apparent 
discs, we do not know precisely their size ; but, 
knowing their distances, we can make certain that 
none of them exceed one hundred and sixty miles 
in diameter. They are the infants of the plane- 
tary family — the fledglings of the planetary flock 
— the pinnaces and nautiluses of the planetary 
fleet. As to the comets ; they are of all sizes, 
from mere specks of a score of miles across, to 
such a mighty cloud as the great comet of 1811 
with its head of 947,000 miles in diameter, and 
train of one hundred and thirty-two millions in 
length. However, the same comet varies exceed- 
ingly in size, expanding as it approaches the sun 
and contracting as it retires into the frosty sub- 
urbs of the system. 



VELOCITIES OF PLANETS. 11? 

So we see that, while many of our astronomical 
neighbors are smaller than the earth, some of 
them are vastly larger — so much larger that 
the earth is a mere babe by the side of them. 
But we must not fall out of conceit with our 
little planetary home. The bulkiest bodies are 
not always the best. The largest homes are not 
always the happiest. The largest empires are 
not always the most prosperous, or powerful even. 
Would you see a famous land ? Look to little 
Greece, and not to mammoth China. Would 
you see a theater of great actions and sublime 
events ? Look to little Thermopylae, and little 
Austerlitz, and little Calvary — not to New York 
nor London. Still, it does undoubtedly tend to 
modesty in us to compare the narrow limits of 
our present abode with the magnificent propor- 
tions of such planets as Saturn and Jupiter, and 
especially of the tremendous sun ! We are 
obliged to confess ourselves and our home mere 
atoms. And if we are so happy and so philo- 
sophic as to have a religious turn of mind, per- 
haps we shall bow our heads and say, " What is 
man that Thou art mindful of him ! " 

See now the wonderful velocities that must 
prevail among some of these great bodies ! Know- 
ing their mean distances from the sun and their 
periods, we readily calculate their average hourly 
pace on their orbits. Mercury moves one hun- 
dred and nine thousand miles an hour, Venus 



118 FOURTn LECTURE. 

eighty thousand, Earth sixty-eight the isand, Nep- 
tune eleven thousand, the comet cf 1680, at 
its fastest, eight hundred and eighty-four thou- 
sand miles an hour. We have wondered at the 
great pace of the eagle, of the winds, of the can- 
non-ball, of the moon with her fifty-four thou- 
sand miles a day ; and yet the moon, on her 
monthly journey about us, is but an indifferent 
traveler compared with the most leisurely of the 
planets. They all seem as if on some urgent 
errand — some errand of life and death. When 
one is resting his weary body from a third to a 
half of his whole time, and happens to think of 
the tremendous and remorseless activity of those 
great revolving spheres, he is discontented with 
himself. What miraculous fleetness ! What if 
those flying orbs should, through some want of 
balance in the system, encounter each other in 
mid-heaven ! 

We weighed off the earth against a Scottish 
mountain. We weighed off the moon against the 
earth, by means of the tides. Can we not also 
weigh the other planets, and even the sun itself, 
in some great astronomical balance ? Yes : one 
of the easiest things in the world — at least so far 
as the sun is concerned. And, first, we may 
weigh the sun, as we did the moon, by means of 
the tides. Another method is by comparing the 
curvatures of the terrestrial and lunar orbits. 
In this way, we really compare the attractions of 



MASSES AND DENSII.ES: 119 

the sun and earth at different distances ; for, of 
course, the degree of curvature depends on the 
force of gravity at the center. A simple propor- 
tion will then compare their attractions — that is 
to say, their quantities of matter — at the same 
distance ; since they vary inversely as the squares 
of the distances. In this way we may find that 
the sim has three hundred and fifty-two thousand 
times the earth's quantity of matter. It would 
weigh down three hundred and fifty thousand 
earths ! The philosopher sits with scales in his 
hands — as Homer says Jupiter did on Ida, to 
weigh the contending fates of Greece and Troy. 
He puts the earth into one scale, and rolls the 
sun into the other. Instantly the earth flies aloft 
with tremendous precipitation. He throws in 
two worlds like ours — ten — one hundred — one 
thousand — with scarcely better success. In a fit 
of impatience, he trundles all the earths he has 
into the capacious scallop. At last an equipoise 
seems establishing: the scales hang see-sawing ; 
and, at last, settle into motionlessness at the same 
level. With mingled curiosity and astonishment 
he counts up those terrestrial globes, and finds 
Ihem three hundred and fifty-two thousand in 
number. Knowing the quantity of matter in the 
sun and its size, we can find its density, or rela- 
tive compactness of matter, to be only one-quarter 
that of the earth. In a similar way, we may find 
the masses and densities of all the planets that 



120 FOURTH LECTURE. 

have satellites with orbits of known dimensions. 
As to those planets which have no such satellites, 
their masses are known from their effect in dis- 
turbing the motions of their nearest planetary 
neighbors. For example, compare the curve 
which the earth when nearest Venus actually de- 
scribes with that we should describe in case 
Venus exerted no attraction on us, and we have 
a measure of her attracting power or quantity of 
matter. So of the rest. In these ways we can 
reach the following results. Jupiter and Uranus 
have about the density of water ; Mercury, Venus, 
Earth, Mars, a density from five to six times 
greater ; while Saturn and Neptune have scarcely 
more than one-tenth of the solidity of our own 
globe. Though comets are so numerous — mil- 
lions, in fact — and some of them occupy such 
immense spaces, the quantity of matter in the 
total of them is exceedingly small; estimated by 
careful men at only ^qVo °^ tuat contained in 
the earth. You can see stars through their 
trains, and sometimes through the very nuclei. 
They have sometimes passed very near to planets 
without sensibly disturbing their motions. They 
are mere planetary fogs. And, summing up, it 
appears that the sun contains more than eight 
hundred times as much matter as all the ether 
members of the system put together. 

All the orbits of our system are continually 
undergoing small changes, through the mutual 



PERTURBATIONS. 121 

attractions of its various members. They ex- 
pand, they contract, they rock, they turn com- 
pletely round in the same plane, their points of 
intersection with our orbit travel round through 
the whole circumference of the heavens. This 
fact gave rise, years ago, to much perplexity, 
many hard problems, many grave fears. It was 
feared that these gradual changes might so com- 
bine and accumulate in process of time as to 
throw the whole system into disorder and wreck, 
dashing planets against planets in hideous con- 
cussion and disaster. At last the great geometers 
Euler, La Place, and La Grange, undertook to 
settle mathematically whether the changes in the 
orbits were of such a nature as to conduct to 
such a deplorable issue. At last the mighty 
problem stood resolved. It was found that, in 
the particular case where the central body of a 
system is vastly heavier than all the rest, and all 
the planetary orbits nearly circular, and nearly 
in the same plane, and traversed in the same 
direction — all of which features, as we have 
seen, belong to our system — there are two 
things about every orbit that can never change ; 
viz., the greater axis and the period. For exam- 
ple, our mean distance from the sun, as found 
for a single revolution, can never vary ; nor can 
the length of our true year. Next, it was proved 
that in such a system all the changes that do 
occur must be periodical, flowing and ebbing like 



122 FOURTH LECTURE. 

the tides of the sea — enlarging for perhaps mil- 
lions of years, and then returning to the old 
point. So the stability of the system stands de- 
monstrated. It has in itself no seeds of death. 
The invisible bonds of the law of gravity hold the 
amazing leviathans of the sky so strongly and 
surely that they can not escape from their spheres. 
The system was built capable of standing for ever. 
And yet how easily it could have been otherwise ! 
Suppose the sun had not been made vastly heavier 
than all the other bodies ; suppose Deity had 
not so tempered the projectile force, in amount 
and direction, to the force of gravity of each 
planet as to make it describe nearly a circle ; 
suppose he had shot off the planets at all sorts 
of angles with reference to each other — and he 
might have done each of these things ; indeed it 
required care not to do them — then the system 
would have been unstable, and, sooner or later, 
our whole Congress of worlds would have gone 
plunging together in frightful and unutterable 
catastrophe. 



V. 

HIGHER SYSTEMS. 



123 



V. Higher Sys' ems. 

i. SUN SYSTEMS 125 

2. GROUP SYSTEMS 137 

3. CLUSTER SYSTEMS 138 

4. NEBULA SYSTEMS 140 

5. ULTERIOR SYSTEMS ........ 14& 

6. ULTIMATE SYSTEM 148 



124 



FIFTH LECTURE, 



HIGHER SYSTEMS. 

AS an example of the Satellite Systems, I have 
described the earth and the moon. As an 
example of the Planet Systems, I have described 
our sun with its revolving planets and comets. 
We come now to systems of the Third Order — 
Sun Systems — each of which consists of two or 
more planet systems revolving about their com- 
mon center of gravity. 

More than six thousand fixed stars, so called, 
that appear single to the naked eye or to some 
powers of the telescope, are found to consist, each 
of several stars, when proper glasses are brought 
to bear upon them. Some are double, some triple ; 
and in one case six stars are found to make up 
what appears a single star to the uc assisted eye. 
The list of these compound stars enlarges every 
year. Recently, a very important addition has 
been made to the list by the discovery that great 
Sirius, the glory of our winter nights, is double. 

125 



126 FIFTH \ECTURE. 

An American has the honor of this discovery, and 
of receiving for it the La Lande prize from the 
French National Institute. 

It is to certain of the double stars that I would 
first ask your attention. Look at the bright star 
Castor. Had you a good telescope bearing on it, 
you would find it to consist of two nearly equal 
members. And, could you follow from year to 
year the bearings of these two members with re- 
spect to each other, you would, in time, find one 
of them in course of revolution about the other — 
just as the moon is about the earth, and the earth 
about the sun. What does this mean ? Why, it 
means one sun with its attendance of planets re- 
volving around another sun with its attending plan- 
ets. That these stars in Castor are self-luminous 
bodies we know from the character of their light, 
as well as from the impossibility that bodies shin- 
ing by mere reflection of light from our remote 
sun or from any neighboring star equally remote, 
should be visible at sucli vast distances from us 
as all the fixed stars must be. That each of 
these suns is the center of a planetary cohort 
that brilliantly escorts him on his way, we infer 
from the analogy of our own system and from the 
wisdom of the Creator. When we see a lamp in 
a house, we infer the neighborhood of some per- 
sons who need the light ; when we see the pier- 
cing Fresnel blaze of the light-house pouring far 
and wide across the darkling seas, we believe in 



SUN SYSTEifS. 12/ 

roving ships to be guided and benefited by it ; 
and when we lift oiir eyes to where a sun blazes 
as a celestial Eddystone through pitchy space, we 
conclude that there are bodies needing to be 
lighted and cheered by its beams, just as the bodies 
of our planet system need to be lighted and 
cheered by our solar orb. Thus we have a new 
and higher order of systems for our astronomy. 
Behold a sun revolving about a sun, a planet sys- 
tem about a planet system ; necessarily, two planet 
systems about their common center of gravity. 

Now more than a hundred such pairs of stars 
have been caught in the act of revolution. The 
Pole Star is one of them. A famous star in the 
Constellation of the Swan, known as 61 Cygni, 
is another. In the case of some of these stars, a 
complete revolution has been accomplished since 
attention was directed to them ; in one case, two 
full revolutions have been completed. But these 
revolving suns are not confined to sets of two. 
There are sets of three, of four, of more stars — 
in each of which the members have about the same 
brightness and distance from each other, and are 
in the course of years observed describing curved 
lines among themselves. Evidently, more systems 
of the third order — suns with their escorts of 
planets revolving, without any intermediate mo- 
tions, about their common center of gravity. In 
addition to these systems whose revolutions we 
see, there arc multitudes of others whose revolu- 



128 FIFTH LECTURE. 

tions we do not see, on account of their distance 
or slowness ; but of which we are just as certain 
as if we saw them. Since the beginning of the 
century, has ripened one of the most important of 
the sciences, under the name of the Calculus of 
Probabilities — a branch of that subtle and power- 
ful Differential and Integral Calculus which has 
served the Prosperos of astronomy, not only to put 
a girdle around the earth, but also around the 
whole visible heavens. According to this science, 
there is no chance worth considering, that any stars, 
optically so close together as to appear single to 
the naked eye, are not actual neighbors in 
space, and so in course of mutual revolution. 
This principle gives us more than a thousand ad- 
ditional sun-systems. But these are not all. 
Many stars that do not appear single to the naked 
eye are proved to constitute similar systems, by 
the identity of what are called their proper mo- 
tions. Thousands of stars are found creeping 
along the sky, not on curves, but on straight lines. 
The progress is exceedingly slow — scarcely aver- 
aging more than ys.oTo °f the moon's apparent 
diameter per annum. Now, whether this is due 
to our own motion, or to that of the stars them- 
selves, or to both, it could not be the same both 
in amount and direction, in the case of two or 
more optically near stars, without their being 
actually near each other in space, and so forming 
a mutually revolving system. This principle en- 



SUNS YSTEMS. 1-9 

ables us to make another large addition to the 
number of our sun-systems. Yonder are Mizar and 
Alcor, two stars in the tail of the Great Bear, 
more than a third of the moon's diameter apart, 
which are thus proved to compose a sun-system. 
They are creeping across the sky hi company ; 
going in just the same direction, and at just the 
same pace. From satellite neighborhoods we 
have risen to planet neighborhoods ; and now, 
from these, we have evidently risen to grand solar 
neighborhoods, where orbed suns go grandly 
wheeling about suns, carrying with them in insep- 
arable union their glittering retinues. 

How far from us are these sun-systems ? At 
one time astronomers almost despaired of being 
able to answer this question. They found that 
the method used for finding the distances of the 
moon and sun from us would not apply to the 
fixed stars. No change in our place on the earth, 
though it has a diameter of eight thousand miles, 
caused the slightest change in the apparent place 
of any of those twinkling points. If we could 
only travel off two or ten times eight thousand 
miles on a straight line ! Well, can you not — 
do you not ? Do you not, every year of your life, 
make a vastly greater travel than that ? Is not 
the earth sailing away with you about the sun at 
the rate of sixty-eight thousand miles an hour, 
and so at the ends of every six months putting 
you at the opposite extremities of a straight line 



130 FIFTH LECTURE. 

one hundred and ninety millions of miles long ? 
So observers set themselves to see whether such a 
monster base line as the diameter of the earth's 
orbit would make any impression on the places 
of the fixed stars. Their triangles informed them 
that in case a star should be displaced on the sky 
less than the eighteen-hundredth part of the 
moon's apparent breadth, by their going that im- 
mense distance, it must be more than one hun- 
dred thousand times that distance from them. 
And they could not find any star that showed a 
clear annual displacement of even that small 
amount. So they put up their bulletin, and in- 
formed the world that no fixed star could be 
nearer to us than one hundred thousand times one 
hundred and ninety millions of miles. A most 
bewildering distance ! It would take light itself, 
that fleetest of known travelers, that Mercury of 
science, whose pace is one hundred and ninety- 
two thousand miles a second, more than three 
years to sweep across it. Here it was feared our 
knowledge must end. We could tell the point 
from us within which the fixed stars could not be ; 
but their actual distances, who could ever know ? 
But Providence was kind. It gave the world, at 
length, a Bessel to bridge over that tremendous 
chasm between us and the sun-systems of remote 
space, and set up mile-stones along it — a man 
who found himself able to measure a smaller bit 
of the sky than one second, who found that by 



SUIT-SYSTEMS. 131 

management he could make sensible in his as- 
tronomy even so trifling a fraction as the thou- 
sandth part of a second — a man who could not, 
indeed, like one of his countrymen, write him- 
self, " By the grace of God, King of Prussia," but, 
what was far better, who could write himself, 
" By the grace of God, King of Prussian astron- 
omers." He found that, by going over the whole 
diameter of the earth's orbit, one would alter the 
apparent place of the double star 61 Cygni about 
one-third of a second. This makes its distance 
from us three hundred thousand times one hun- 
dred and ninety millions of miles — an interval 
which it takes light nine years to traverse. 

This was in 1838. Since then, about forty stars 
have yielded up their distances from us to our 
curiosity. The nearest sun-system yet found be- 
longs to the southern hemisphere — Alpha Cen- 
tauri, the brightest star in the Centaur, and in- 
deed in the whole southern vault. This is only 
one-third as remote as 61 Cygni. The Pole Star 
system, on the other hand, is five times as remote 
— one million five hundred thousand times one 
hundred and ninety millions of miles. The mar- 
iner and the fugitive have used light to guide 
them on their way which has been forty-six years 
in coming to them for that purpose. 

One would like to know how large these re- 
volving suns are ; how they compare in this re- 
spect with our sun. If they showed real diame- 



132 FIFTH LECTURE. 

ters under the telescope, we could at once make 
the comparison. But they do not. So we are 
driven to another method of a less satisfactory 
kind, but still one that will help us to some just 
idea of how the different suns of space compare 
with each other in magnitude. Delicate instru- 
ments have been invented for measuring the rel- 
ative amounts of light from the heavenly bodies. 
With what is perhaps the best of these instruments, 
it is concluded that we receive twenty-two thousand 
million times the light from our sun that we do 
from the sun-system Alpha Centauri. But that sys- 
tem is two hundred thousand times further away. 
Hence it follows, that, if it were brought as near to 
us, it would give a little more than twice as much 
light as our sun ; that is, each of the two nearly 
equal suns that compose the star is about equiva- 
lent, in the matter of light, to our luminary. In the 
same way we find that the 61 Cygni system gives 
about half as much light as our sun ; making 
each of its two nearly equal members equivalent 
to a quarter of our sun. The Sirius system is 
equal in light to sixty-three of our suns ; the Pole- 
Star system to eighty-six. In each of these, the two 
stars composing the system differ exceedingly 
from each other in brightness, and the larger star 
must be credited w T ith most of the brilliancy. 
Think of an eighty-fold sun ! However, some 
stars are still more astonishing ; Vega, for ex- 
ample, which blazes with the light of three hun- 



SUN-SYSTEMS. 13<f 

dred and forty-four suns ; Capella, for example, 
which blazes with the light of four hundred and 
thirty ; Arcturus, for example, which blazes with 
the light of five hundred and sixteen ; Alcyone, 
for example, which blazes with the light of twelve 
thousand ! As we have seen, our sun is no trifle. 
Its astonishing orb would nearly fill the whole lu- 
nar orbit ; and would weigh down, eight hundred 
times over, its whole ponderous cortege of satel- 
lites, planets, and comets. And yet it is only one 
of the lesser lights of space. Not the smallest, in- 
deed — forbid it, little 61 Cygni — but still a 
mere rush-light and glow-worm as compared with 
many of the huge luminaries which pour their 
glories adown the immensity of nature. It could 
not remain visible a moment in the presence of 
such golden-haired and majestic day-kings as even 
Sirius and Polaris to say nothing of those huger 
monarchs whose effulgence floods the celestial 
spaces. 

Knowing the distance of one of the systems 
from us, we can find how far apart its members 
are at any time, by observing the apparent dis- 
tance between them. The two suns of Alpha 
Centauri are apart by only seven diameters of the 
earth's orbit — something less than the distance 
of Uranus from our sun — so that planets belong- 
ing to the system will sometimes have two suns 
above the horizon at once, while at another time 
one sun will rise while the other sets. The two 



134 FIFTH LECTURE. 

suns of 61 Cygni are apart by twenty-one diame- 
ters of our orbit ; those of the Pole Star by one 
hundred and five diameters ; Mizar and Alcor by 
at least five thousand diameters — five thousand 
times one hundred and ninety millions of miles — 
a line on which could be ranged three hundred 
and sixty planet-systems like ours. 

Several of these systems having made entire rev- 
olutions since they began to be scrutinized, we may 
be said to have seen their periods. Others have 
advanced so far on their orbits that we can readily 
estimate the times required to accomplish the re- 
mainders. And others still have been under ob- 
servation sufficiently long to furnish us with very 
considerable pieces of the curves they describe ; 
from which, like the naturalists, we can build up 
the entire orbits, and press out of them by our 
powerful geometry all their characteristics — 
among other things, the periods and ellipticities. 
The periods differ among themselves wonderfully. 
One is forty years ; that of Alpha Ccntauri is 
seventy-seven years ; that of 61 Cygni four hun- 
dred and fifty-two ; another three thousand ; and 
that of Mizar and Alcor must be something like 
two hundred thousand years ! Wonderful year 
of two hundred millenniums ! Wonderful orbits 
also, as far as observed — wonderful for their el- 
lipticity ! In one case, that of Alpha Cen'tauri, 
the orbit is five times as long as it is broad. 
What extremes this means may be seen from the 



SUX-SYSTE}fS. 135 

case of Halley's comet. This body has an orbit 
four times as long as it is broad ; and the con- 
sequence is, that, while at one point it ap- 
proaches the sun as near as Mercury, at another 
it recedes from it six hundred millions of miles 
beyond Neptune — the least distance from the sun 
being to the greatest as one to eighty-five. Such 
variations would be fatal to an inhabited earth ; 
but to a sun, that movable furnace that carries 
its own light and heat with it wherever it goes, 
what matters it how far it strays off from its cen- 
tral orb into the cold of space — to a sun that is 
never at less than white heat, what matters it if it 
sometimes gets a good deal whiter ! We may be 
sure, however, that those sun-systems which con- 
sist of three or more suns do not contain such 
eccentric orbits. It would be inconsistent with 
their stability. As our planet system would fall 
to ruin were not its orbits nearly circular, nearly 
in the same plane, and controlled by a force at 
the common center of gravity greatly superior to 
any individual force in the system, so would 
every higher system made up of more than two 
members. 

Before dismissing these sun-systems, I must say 
a word as to their color. All the colors of the 
rainbow are represented in them. Some sys- 
tems are white, some blue, some red, some yellow, 
some green ; and this, you will observe, means 
differently colored days for the planets of those 



136 FIFTH LECTURE. 

systems. Castor gives his planets green days. 
The Pole Star gives his yellow. There are more 
than sixty blue systems, one of these consisting 
of a great number of members. In the southern 
hemisphere are stars, yet to be found double, 
which in the telescope look like drops of blood — 
all about the constellations of the Cross and 
Altar, as if to gloriously symbolize the sprinkled 
blood of our redemption. Also the suns of the 
same system often have different colors ; one 
shining like an emerald, another like a ruby, and 
perhaps a third like a sapphire. And, as if t@ 
make that Southern Cross the fairest object in all 
the heavens, we find in it a group of more than 
a hundred variously-colored red, green, blue, and 
bluish-green suns, so closely thronged together as 
to appear in a powerful telescope like a superb 
bouquet, or piece of fancy jewelry. Let no one 
say that the Creator, who makes gems and flow- 
ers for the earth, and sets gems and flowers in 
the sky, cares not for natural beauty : though 
it be most true that the ' beauties of holiness, es- 
pecially from the womb of the morning, when 
thou hast the dew of thy youth,' are still more 
precious in his sight. 

Group-systems 1 Near the bright blue star 
Yega is a star which the telescope finds to be 
quadruple. The four stars are arranged in pairs 
— the pairs being many times further apart than 



GROUP-SYSTEMS. 137 

are the individuals of each pair. The whole 
form a system by themselves; as is shown by the 
sameness in amount and direction of their proper 
motions. But, grouped as they are, the law of 
gravity requires each pair to revolve around its 
center of gravity, and then both pairs about their 
common center of gravity. The revolution is 
not seen, as in the case of many double stars ; but 
we are just as sure of its reality as if we saw it. 

In Orion is a star which the telescope finds to 
be sextuple. The six stars have all the same 
proper motion, and so are neighbors in space. 
Four of them are at about the same distance from 
each other ; but two of these have each a small 
companion much nearer to it than are the others. 
The law of gravity requires each pair to form a 
revolving group by itself, and then all the spheres 
to wheel about the common center of gravity of 
the whole. That superb wheeling is not seen, on 
account of distance ; but we are just as sure of 
it as if we saw it. Another Group-system ! 

Look at the famous and beautiful Pleiades ! 
Gathered about the brightest star of the group 
Alcyone, the telescope sees fourteen conspicuous 
stars. These are all creeping along the sky, 
equally fast and in the same direction. The cal- 
culus of probabilities assures us that the chances 
are hundreds of millions to one against their 
being merely optically connected. They form 



138 FIFTH LECTURE. 

one grand astronomical neighborhood in space, 
around whose center of gravity they all revolve ; 
one grand company of celestial navigators, ex- 
ploring their way by unerring instinct, without 
chart or compass, through trackless space. But, 
if you should see a map of these fourteen stars, 
you would find them distributed into several 
groups, each of which must contain its own cen- 
ter of revolution, while all these centers must be 
borne in majestic sweep about the gravity-center 
of the whole sparkling family. Invisible or- 
bits within orbits ; but as certain as if we saw 
their fiery ellipses burnt into the dark concave 
of evening ! The distance of this group-system 
from us has been determined by the- determina- 
tion of the distance of Alcyone ; and is twenty-five 
million diameters of the earth's orbit. Were the 
Pleiades this moment blotted out of existence, 
they would still blaze away in the neck of Taurus 
for more than seven hundred years ; for that is 
the time spent by light in passing from that sys- 
tem to us. 

These specimens of the group-systems must 
suffice. We pass to the next higher order — 
Cluster Systems. 

There are thousands of small roundish spots 
on the sky which, when examined by telescopes, 
prove to consist of crowded stars ; sometimes 
uniformly distributed ; in other cases, gradually 



CLUSTER-SYSTEMS. 139 

becoming denser till all individuality is lost in a 
general blaze of light at the center ; and in other 
cases still, arranged into several nuclei which lie 
quite evenly over the mottled face of the cluster. 
On examining the nuclei carefully, they are some- 
times found to consist, each, not of a single group, 
but of a cluster of groups. Behold systems of 
the Fifth Order ! The artificial form of each gen- 
eral cluster, and the chasm of black space all 
around it, show that it is a system by itself in 
space, with its one center of revolution for all the 
nuclei. Then each nucleus has its own subordi- 
nate center for all the groups composing it ; and 
next, each group has its still more subordinate 
center for all the suns composing it. Many of 
these great systems must contain from ten to 
twenty thousand stars each. Think of a system 
made up of twenty thousand revolving suns ; each 
sun with its planets occupying at the same time 
a three-fold orbit, and spinning at once around 
three widely separated centers — first, around the 
center of the group ; next, around the center of 
its cluster of groups ; and then, around the center 
of the whole great cluster ! 

As an example of these cluster-systems, I in- 
stance a cluster found in the constellation 
Hercules. It is famous among astronomers as 
being the grandest object of its class in the 
whole heavens. When Sir William Herschel saw 
it for the first time through his great reflector, it 



140 FIFTH LECTURE. 

almost made him leap, with mingled astonishment 
and delight. An eminent astronomer doubts 
whether any person ever saw it for the first time, 
through a large telescope, without a shout of won- 
der. Certainly it is an object of wonderful glory, 
— that golden shield of packed suns ! Shall we 
call it the aegis of immortal Jove ? Call it, 
rather, the flaming buckler of the Christian 
Creator, hung out for sign on heaven's blue bat- 
tlements, and on whose thick bosses those men 
insanely rush who, in the face of the stars, pre- 
sume to doubt Almighty God ! The first Herschel, 
sounding the heavens with his telescopes, con- 
cluded this cluster-system to be deep in the 
abyss several hundred times the distance of the 
nearest fixed star — say some two thousand years, 
as light travels. Its locomotive suns, with their 
long trains of planets, do not, at such a distance, 
render to our eyes those mighty three-fold curves 
on which they are rushing ; but we are just as 
sure of their reality as though we saw them — 
saw them as. we see the orbits of binary stars — 
saw them as we see the track of the rocket when 
it describes its flaming parabola through the air. 

We advance another step, to systems of the 
Sixth Order, — Nebula Systems ! 

Scattered, or rather arranged, over the sky by 
thousands are those bright-misty spots, called 
nebulae, which no power of the telescope has yet 



NEBULA-SYSTEMS. 141 

been able to resolve into stars. It Lis been 
claimed that they do hot consist of stars, but only 
of a sort of fire-mist, out of which suns and 
planets and satellites are in process of being made 
by natural law. There are many objections to 
this view. But it is enough that there is not a 
single proved case of such fire-mist in space ; that 
the hypothesis is altogether unnecessary to ac- 
count for the facts observed ; and that nebulae, 
apparently as irresolvable as any, have, by improve- 
ments of telescopes, been turned into clusters of 
stars. In my view, they all consist of stars, so 
packed together by local neighborhood and un- 
speakable distance that all individuality of im- 
pression on the eye is lost. They are found in 
great variety of singular and beautiful forms — 
sometimes perfectly round, sometimes oval, some- 
times lens-shaped, sometimes ring-shaped and 
even consisting of a series of concentric rings. 
One beautiful nebula resembles a crab ; another, 
a fan ; another, an hour-glass ; another, a whirl- 
pool, whose eddies are made evident to the eye 
by, as it were, floculi torn from the famous 
golden fleece of Colchis. Some of them are 
perfectly continuous and uniform in appearance. 
Others are " spotted as a pard," with numerous 
centers of condensation : while others still are 
broken up into more or less distinctly separated 
nebulous patches ; like a defeated army whose 
great corps are just in the act of separating to- 

■ 



142 FIFTH LECTURE. 

ward all points of the compass. The great frag- 
ments of these routed nebulae appear in the best 
telescopes very much as the cluster-systems do in 
the smaller — that is to say, dappled with nuclei 
pretty evenly distributed. They are evidently 
cluster-systems. And, taken together, they form 
a revolving neighborhood in space, of another 
order still higher — a Nebula System in which 
nebulas of clusters of groups of suns sweep their, 
at least, quintuple orbits in harmonious combi- 
nation around the gravity-center of the whole 
nebula. 

What is the Milky Way, so called, which we 
see belting our heavens ? Nothing but the nebula 
to which we belong, expanded all round the sky 
and easily resolved into stars by the fact that we 
are in the midst of it. A little observation and re- 
flection suffice to show that its shape is that of a 
thick mill-stone, with its rim split in the middle for 
about a third of its length and somewhat opened. 
Our place is near the plane of this cleavage, but 
considerably one side of the center. When we, 
from our place in this cleft wheel of stars, look 
off in the direction of the circumference, the stars 
appear very numerous ; when we look toward the 
sides, we see comparatively few. All the scat- 
tered stars, all the groups, small and large, that we 
see in any direction, belong to our Milky Way — 
to our nebula. They are nearer to us than any 
other stars in space. All the stars whose dis- 



NEBULA-SYSTEMS. 143 

tances have been determined, all the multiple 
stars whose orbits- have been observed, all the 
stars whose proper motions have been noticed, are 
as much part of our Milky Way as the milkiest 
part of it. All the examples of astronomical sys- 
tems which I have hitherto given, at least up to 
the cluster-systems, were from this same nebula 
of ours. And cluster-systems themselves can be 
easily supplied from it. If you will scan on some 
favorable night the remoter parts of this white 
Wonder, you will find that it is by no means a 
continuous nebulous zone, but rather a succession 
of star-clouds, many of which are mottled after the 
manner of the cluster-systems. And such they 
are. The whole, from satellites to sun-clusters, 
are in process of revolution about the great force- 
ful heart of the nebula. We know it must be so, 
in advance of all observation. But in this case it 
is thought that observation has made assurance 
doubly sure. First, our sun is in motion — like 
Castor and Polaris ; like the thousands of stars 
that show proper motions, and, in part, because 
they show them. A wonderful thing has been 
noticed in that part of the heavens that is now 
passing over our meridian southward from the 
zenith ; the region occupied by Orion, the river 
Po, Sirius, and especially the Dove. It has been 
noticed that the stars in this region are gradually 
drawing together, just as the ships of a fleet would 
seem to do to one sailing away from them ; while 



144 FIFTH LECTURE. 

at the opposite quarter of the sky the ^cars are 
gradually separating, just as the ships of another 
fleet would seem to do to one sailing toward 
them. Great Hercules is yearly becoming huger 
and brawnier ; his club, and especially his bow, 
growing every year more formidable. This has 
been going on now for a great number of years. 
Of course, there is but one explanation. Our 
sun, with its retainer-worlds about it, is sailing 
away through space toward Hercules, on an orbit 
so vast that the part of it which has been described 
from the date of the earliest accurate observations 
does not differ sensibly from a straight line. At 
last, however, we shall double the wondrous cape 
of our great ellipse ; and then the Dove will begin 
to expand and plume her heavenly wings, while 
champion Hercules Avill dwarf behind us. But 
this does not determine where the center of mo- 
tion is. Where is it ? Astronomers have sought 
to answer this question, and apparently not in 
vain. By methods which can not now be ex- 
plained, it is found that Alcyone — most beautiful 
star of the beautiful Pleiades — is the center of our 
motion ; and that we are moving about it at the 
rate of more than thirty-three millions of miles a 
year, on an orbit whose diameter is fifty million 
times larger than that on which we move about 
the sun. As the distance of Alcyone is approxi- 
mately known, we can find our period. It is only 
about twenty millions of years. 



NEBULA-SYSTEMS. 145 

Such is our sun's center of motion. And the 
celebrated Maedler-has shown that it is also the 
center of a great number of other suns — in fact, 
that the proper motions of the stars in all quar- 
ters of the heavens conform to the idea that they 
are spurring in glorious curriculum around the 
same point. He concludes that Alcyone is the 
center of the whole nebula. And though the 
English Astronomer Royal has recently dissented 
from this conclusion, and though we certainly are 
not authorized to claim for it the most absolute 
proof, yet it is probably as much like the truth as 
most photographs are like the persons who sit for 
their pictures to the sun. 

Mysterious continental islands of the remoter 
heavens ! Greatest empires of suns that have 
yet sent greeting light to us ! There ye lie to- 
night, seemingly steeped in breathless quietude 
and uttermost sleep, where the earliest observer 
saw you : and yet what mighty race-c v mrses are 
those on which your orbs go panting their eternal 
rounds about the great nebular heart ! Why, let 
us measure two of these celestial Astrodromes. 
According to the best estimates of our own neb- 
ula it contains some eighteen million suns ; and 
the thickness of its golden wheel is about eight 
million diameters of the earth's orbit, while its 
diameter is one hundred and seventy million such 
diameters. One of its Border States would re- 
quire not far from one hundred millions of y°ars 
10 



146 FIFTH LECTURE. 

to put orbit about metropolis Alcyone ; and, 
though so remote, has never been in danger of 
parting company with us. There is the oval ne- 
bula of Andromeda, just visible to the naked 
eye and yet giving no sign of resolvability in the 
six-foot speculum of the Earl of Rosse. A nebula 
of which such things are true, is easily shown to 
be so far away that the light by which we see it 
must show it as it was at least a million of years 
ago, instead of as it is to-night. The rays have 
been all that time charging across the void at the 
rate of 192,000 miles a second. At such a dis- 
tance, its apparent diameter, half that of the 
moon, means for the nebula a breadth of thirty 
thousand years — the fifty-three foot reflector 
being surveyor-general, and a light-sprite carry- 
ing the chain. 

We have found all the suns, and groups of 
suns, and clusters of groups of suns, in each neb- 
ula, engaged in revolution about its center of 
gravity. Is this center itself in motion on another 
orbit still larger ? Is each nebular fleet, instead 
of riding at anchor in the sky, sailing away on a 
circumnavigation more stupendous than any we 
have yet noticed ? It is even so. There are 
Ulterior Systems. We find nebulae disposed in 
groups of two or more ; of about the same bright- 
ness, coming into view with about the same power 
of the telescope ; evidently belonging to the same 
order of distances from us. Just as there are 



ULTERIOR-SYSTEMS. 117 

double and multiple stars, so there are double, 
triple, quadruple, 'quintuple, sextuple nebulae ; 
and recently D'Arrest, a Danish astronomer, has 
announced that he has actually caught a nebula 
in the act of revolving about a nebula. Very 
likely he is mistaken ; it seems as if he must 
be ; in any event, we need no sucli ocular dem- 
onstration. We have long been as sure of re- 
volving nebulae as if we had seen them — sure 
of some Alcyone, 12,000 suns strong, revolving 
about another Alcyone, perhaps 100,000 suns 
strong. More than this. The Magellanic Clouds, 
so called, of the southern hemisphere, are nothing 
but two great beds of clusters and nebulae ; three 
hundred nebulae in one, and thirty-seven in the 
other : and in the constellation Virgo, especially 
in one of its wings, the nebulae are scattered al- 
most as the grain will be sown in your fields this 
spring — swarms of them, in groups and clusters 
of groups ; and it is just as certain that each of 
these great beds is in course of revolution about 
its center of gravity as it is that over that amaz- 
ing congeries of firmaments is stretched the scep- 
ter of law. 

Mightiest of astronomical neighborhoods \et 
seen ! What wondrous outskirting orbits have 
we here — what abysses of periods — what year 
Great and Wonderful in which some picket sun 
of one of those picket nebulae spins out its ellipse 
about the whole nebulous stratum to which it 



148 FIFTH LECTURE. 

belongs ! What abysmal grandeurs of motion 
are piled and compacted within that circle of 20° 
diameter about the wing of Virgo ! The ancients 
did not know what wonders were swarming in 
this region ; and, had they known, they could 
hardly have covered its flying hosts with a more 
appropriate symbol than they have done — a 
broad celestial wing. You easily understand the 
utter inadequacy of figures, whether expressing 
miles or diameters of the earth's orbit or the largest 
measured distances of fixed stars or years of light- 
motion even, to express the dimensions of this 
Titanic nebular system. 

Such are the various orders of systems which 
we can prove to be within the range of our tele- 
scopes. But no astronomer doubts that within 
this range may lie hundreds of different orders, 
wheel within wheel, in astounding climax and 
bewildering complexity : even that within this 
range our own earth may be describing a thou- 
sand-fold orbit about a thousand different centers. 

But there must be, at last, a Universe System 
— a system composed of all the bodies that people 
space, and in which each body revolves about the 
gravity-center of the whole material universe. 
Let us devote a few thoughts to it. 

Eighteen million suns belong to our firmament. 
More than four thousand such firmaments are 
visible ; and every increase of telescopic power 
adds to the number. Where are the frontiers — 



UNIVERSE-SYSTEM. 149 

the last astronomical system — that remote spot 
beyond which no nebula, no world, glitters on the 
black bosom of eternal nothingness ? Probably, 
some one of those many nebulae just brought 
into faint view by the great reflector at Rosse Cas- 
tle, is but another nebula of Andromeda ; which, 
though visible to the naked eye, gives no sign of 
being resolved into stars by an instrument of four 
hundred times the eye's space-penetrating power. 
Think of the distance expressed by four hundred 
times the distance of the milky way of Androme- 
da — five millions of years, as flies the light ! 
Alas, how feeble are our powers ! How they la- 
bor and bow under the weight of such mighty 
numbers — such gates of Gaza ! What wondrous 
chronometers those must be which could take fit- 
ting account of the ongoings of such far-off firma- 
ments ! Could you stand, with a wand in your 
hand reaching to that remotest galaxy, and sweep 
it around you in every direction, what an empire 
fit for a Jehovah would fall within the embrace 
of those glorious circles ! And ye-t who shall say 
that even this is the whole astronomical universe ? 
What right have we to stop just where the power 
of our instruments happens for the moment to 
have stopped, and say, "This is the end — these 
are the Pillars of Hercules ? Turn back, ad- 
venturous explorer — nothing but night and void 
in this direction — thou hast reached the last 
outpost of the kingdom of the Eternal ! Ne phis 



150 FIFTH LECTURE. 

vltra ! " No : thrice no. On still through peo- 
pled infinitude, through raining galaxies and 
tornado-nebulae; and, while thou goest outward 
still through the charging, storming hosts of suns 
as long as thought can fly, or angels live, say ever 
to thyself, " Lo, these are parts of his ways ; but 
how little a portion is heard of him ! The thunder 
of His power, who can understand ? " Is not space 
infinite ? Is not He infinite ? And who dare 
say that his works are not wellnigh infinite too 
— at least that the limit to which our gasping and 
bewildered astronomy has hitherto conducted us 
is not, as it were, but the first mile-stone of peo- 
pled space ; and that great swarming sphere which 
our mightiest telescopes have gauged, but the 
merest rain-drop compared with another swarming 
sphere which embraces it ? But let us suppose 
an end ; suppose an orbit so large as to include 
in its unspeakable round the entire magnificence 
of the sidereal heavens. At last the Ultima Thule 
is reached. We have the total universe of matter 
which God has made — one all-comprehending as- 
tronomical neighborhood — and around it stretches 
in all directions the black wastes of an altogether 
endless vacancy. All members of this great ulti- 
mate system must be in motion about its common 
center of gravity. Whether this sublime center 
is, or is not, a mathematical point, where not an 
atom of matter nestles, our present science has no 
means of determining. But is there not some- 



UNIVERSE-SYSTEM. 151 

thing at the bottom of our hearts better than sci- 
ence, which invites .us to believe that what would 
be so fitting and beautiful is also triumphantly 
actual ; namely, that at the center of this august 
totality of revolving orbs and firmaments — at 
once the center of gravity, the center of motion, 
and the center of government to all — is that better 
country, even the heavenly, where reigns in glory 
everlasting the Supreme Father and Emperor of 
Nature ; the capital of creation ; the one spot 
that has no motion, but basks in majestic and per- 
fect repose while beholding the whole ponder- 
ous materialism which it ballasts in course of cir- 
culation about it. All hail, Central Heaven ! All 
hail, innermost Sun Palace and celestial Alham- 
bra ! All hail, believer's Last Home — from 
which an adult astronomy, fitted with the pictured 
and dynamical wings of angels, shall immortally 
radiate to all the girdling worlds and immortally 
bring home fresh proofs of the glory of Him who 
has so long been defrauded of His rights among 
men of science by the empty names of law and 
nature ! 



VL 

AUTHOR OF NATURE, 

AS RELATED TO ITS LEADING FEATURES. 

153 



VI. Author of Nature, 

As Related to its Leading Features. 
i. VASTNESS 59 

2. VARIETY IN UNITY 163 

3. FINISH OF MINIMA 168 

4 WISDOM 171 

5. DYNAMICS 177 

6. RELATION TO LAW .182 

7 RELATION TO TIME AND MOTION . . . .188 

8. MYSTERY 193 



154 



SIXTH LECTURE. 



AUTHOR OF NATURE. 

IS there an Author of Nature ? Hitherto, the 
affirmative has been steadily assumed ; and 
I hope that at this point such a question seems 
almost an insult to your understandings — freshly 
returned as they are from sweeping through the 
unutterable glories of the astronomical universe. 

Still, let the preposterous question be enter- 
tained. We are not likely to realize too vividly 
the existence of an invisible Divinity. Though 
we are not atheists ; though we would be shocked 
to receive that dreary and awful name ; though 
perhaps it has never once occurred to us, with 
our Christian training and surroundings, to doubt 
that this glorious nature about us has the God of 
the Scriptures for its Father and King, we still 
belong to that fallen race whose strong and uni- 
versal tendency is to be without God in the world. 

Theists and atheists agree as to the advantage 
of approaching the question of a Divine Being 

155 



156 SIXTH LECTURE. 

with a mind freshly steeped in the leading facts 
and courses of nature. The atheist claims that 
nature makes on minds thoroughly imbued with 
her spirit an impression adverse to faith ; and 
points in evidence to some eminent cultivators 
of the physical sciences who have been as skep- 
tical as they have been scientific. So he is in 
favor of the study of nature. On the other hand, 
the theist is in favor of it for the very oppo- 
site reason. He denies the atheism of science. 
He refuses to infer it from the unbelief of some 
French and German philosophers — with here and 
there a second-rate English disciple — whose 
minds from childhood have been poisoned with 
the writings of Yoltaire and his school, who have 
seen around them only a grotesquely corrupted 
form of religion, and whose private lives for the 
most part were such as to make it greatly for 
their interest to have no God. To him the case 
of such exceptional men only shows the exceed- 
ing force of native depravity, evil training, evil 
surroundings, and evil habits, at withstanding 
the natural tendency of their pursuits. This 
tendency he regards as strongly theistic. He 
thinks he sees premonitions, prophecies, presump- 
tions, and even proofs of Divinity in the great 
universe that expands around him ; and believes 
that, other things being equal, the more fully 
one comes under the influence of the astronomy, 
the geology, and the other branches of natural 



AUTHOR OF NATURE. 157 

science whose findings have amazed mankind, 
the more easily he will admit and the more 
strongly he will hold, the doctrine of a Divine 
Being. 

What all classes think it well to do, let us at- 
tempt. We will attempt to place our hearts still 
more fully en rapport with nature. We will, if 
possible, get them into yet closer communication 
and sympathy with its great leading facts and 
courses. These are chiefly astronomical. Yet I 
shall not restrict myself to astronomical facts, 
technically so called, but shall allow myself to 
gather from the whole of that broad field of 
science of which astronomy is the undisputed 
and all-comprehending Chief. And I can not but 
think that the effect will be to preclude objec- 
tions, to furnish presumptions, and generally to 
dispose the mind to a mighty faith in God. I 
am persuaded that any man who can be fairly 
set down in the midst of nature, and thrown 
honestly open to all its subtle inductions, mag- 
netisms, inspirations, will silently drink in theism, 
as a fleece spread out under the stars drinks in 
the dew. 

Suppose it claimed that a certain veiled paint- 
ing is the work of Titian. If, on gradually lifting 
the veil, we find exclusively trait after trait such 
as might have been expected in a woik by that 
great master, our disposition to think favorably of 
the claim increases with every step : and if, when 



158 SIXTH LECTURE. 

the canvas is entirely exposed, every leading fea- 
ture seems Titian ic and the whole worthy of 
such an author, our minds are far advanced 
toward faith — they are in a state of high prep- 
aration for any ulterior evidence, and only com- 
paratively little of it will be required to secure 
full conviction. And this is reasonable. Pre- 
vious to examination, how could we be sure that 
there were not lurking under that veil incompat- 
ibilities, or at least disagreements ? Now our 
uncertainty is removed. We have found positive 
harmonies. The facts match the claim. The 
picture is such as might have been expected from 
Titian - - such indeed as he would surely have 
painted. His great characteristics are strikingly 
here. And these are so many verisimilitudes, so 
many presumptions in favor of the claim : and, in 
the absence of all evidence to the contrary, at 
least authorize the critic to stand at the very 
verge of assent, facing it kindly and with foot 
uplifted, ready to cross the border at the first 
competent invitation. Let such an invitation 
come in the shape of an assurance that the paint- 
ing is almost universally accepted as the work of 
Titian, especially among the most intelligent and 
fair-minded judges; further, that the hypothesis 
which ascribes the work to him is, as compared 
with other hypotheses, altogether the simplest, 
the least embarrassed, the most useful, as well as 
the most historical — this would and should plant 
his feet in the very center of faith. 



VASTNESS OF NA1 URE. 159 

Now it is claimed that nature is the work of 
God. Let us, step by step, unveil its leading 
features and see if they do not strikingly harmo- 
nize with the claim : and, as they may be found 
to do so, let unbelief approach its frontier ; and, 
when at last the general scheme of nature appears 
characteristic and worthy of God, let the traveler 
at least stand on the last boundary of his chill 
and somber territory, all ready to cross with de- 
cisive and ringing step into a brighter land at 
the first summons of the positive evidence. 

What I propose, then, in the present lecture, is 
to illustrate the general harmony between nature 
and the doctrine of a God. Of course, a few 
specimen illustrations are all that can be offered. 
One will do well to feel the pulse of nature still 
more fully in the works of Ray and Good and 
Paley, in the Bridgewater Treatises, and in later 
works of the same character. 

One of the most striking features of what we 
call Nature is its vastness. 

I do not forget that I am speaking to those who 
have become familiar with the wonders of physical 
science. But neither do I forget that even the 
scholar must refresh his impressions of things in 
very much the same way with other men. So I ask 
you to think of plains stretching to the horizon ; 
of mountains piercing the clouds ; of roomy con- 
tinents anchored in roomier oceans ; of this whole 
earth-sphere, with its huge baldric of twenty-five 



160 SIXTH LECTURE. 

thousand miles, covered with innumerable ve- 
getable products, peopled with men to the poten- 
tial figure of a thousand millions, swarming still 
more potentially with the lower animals, and so 
flooded with microscopic life that almost every 
cubic inch of air and water and soil is panting 
with an incalculable population, — some of whose 
smaller individuals multiply themselves into 
one hundred and seventy billions in four days ; 
gather their five hundred millions in a single 
drop of water ; and yet make up, with the stony 
cerements of the merest fraction of their fossil 
ancestry, whole mountains and geologic beds. 
Such is our world. Out in yonder vault, find 
that millionfold world which we call the sun, 
with its invisible retinue of a hundred earths • 
out in yonder vault, when night falls, find a 
thousand suns similarly attended ; with tube 
Galilean, thousands more; with tube Herschel- 
ian, millions more ; with tube Rossian, billions 
more. Is this the end ? What astronomer for 
one moment imagines that another enlargement 
of the great speculum at Parsonstown would 
show our vision to be already hard up against 
the frontiers of nature ? Not even Darwin doubts 
that successive improvements in the space-pene- 
trating power of our instruments would go on 
indefinitely opening up firmaments at qyqyj step. 
Where is the verge of the universe ? Who would 
undertake the roll-call of its orbs ? Who dares 



VASTNESS OF NATURE. 161 

to say that he could count through the grand 
total of its firmaments, even though he should 
count a thousand years ? Figures go but a small 
way toward expressing the dimensions of such a 
universe — whether one considers the number of 
its worlds, or the expanse of space through which 
they are distributed. Our world spins round its 
ellipse, of well-nigh two hundred million axis, 
without ever having a neighbor nearer than 
thirty millions of miles, save its own moon. 
The interval between our sun and the nearest 
star of the same galactic nebula is twelve hun- 
dred thousand times this distance. And then 
the distance from nebula to nebula — it is abso- 
lutely awful. Our telescopes sweep a sphere of 
stars whose diameter is seven millions of years, as 
light travels. Calculation covers its abashed face 
with its great wings in the presence of these over- 
whelming amplitudes. And such is nature ! 

Certainly such a universe as this does not cry 
out against the existence of a God whose essen- 
tial attribute is immensity. On the contrary, it 
is just such a universe as one would have ex- 
pected to come from such a being. Nay, given a 
Deity who is practically at home in every point 
of space, whose attributes are laid out on a scale 
of unbounded vastness, to whom it is just as easy 
to make and govern a trillion of worlds as it is a 
grain of sand, and the imperial fitness of things 

would demand that 1 e people vacancy with very 
11 



162 SIXTH LECTURE. 

much that profusion and breadth >f being that 
we actually see. The work ought to express and 
honor the workman. And when I am told of an 
author of nature who is immense with a three- 
fold boundlessness of intelligence, might, and 
years ; so that to him our great and small, our 
far and near, our center and circumference — 
though that circumference sweep around all the 
expanses of modern astronomy — are practically 
the same ; so that he can properly challenge, "Do 
not I fill heaven and earth ? " — when I am told 
of this, and I then place myself out under the 
open dome of nature, amid its exuberant objects 
and marvelous stretches, I feel myself silently 
drinking in predispositions to faith as the fleece 
spread out under the open heaven drinks in the 
dew. I feel that the doctrine matches facts ; that 
the theory has in its favor a comprehensive veri- 
similitude and presumption ; that Nature, instead 
of saying, " There is no immense God," signifi- 
cantly asks, in a tone of encouragement and with 
a look of incipient expectation, "Is there not such 
a Being ? " In fine, I feel that our slight lifting 
of the veil from the painting has disclosed a fea- 
ture strikingly characteristic of the great master 
to whom the work is attributed — a feature which, 
in the absence of all counter-evidence, naturally 
sets our faces faith ward — one, of several har- 
monies which, as successively presented, will war- 
rant us in looking faithward with evergrowing 
kindliness of aspect. 



VARIETY IN UNITY. 165 

Notice with me the variety in unitj that char- 
acterizes Nature. 

Some hundreds of millions of creatures on our 
earth are so much alike that we put them into a 
class by themselves and call them men. They are 
all alike in certain fundamental features ; and yet 
each man differs materially, both in body and soul, 
from every other man. So of every other class 
of things — animal, vegetable, inorganic ; while 
there is a sub-stratum of unity among the mem- 
bers of each, on account of which they are 
classed together, there is not one which is not 
very unlike, in many respects, all its fellows. All 
animals have great points in common : but how 
many, many sorts of animals ; and how great the 
difference between the eagle and the microscopic 
mote, between the cetus and the polyp, between 
the most perfect man (body and soul) and the 
rudest of the polypi ! All vegetables are similar- 
ly constituted : but whose memory can master all 
the distinct kinds of vegetables in the wide inter- 
val between the spire of grass and the huge tree 
that wrestles victoriously with stormy centuries ; 
and reckon up the great differences that exist, as 
to shape and size and color and flavor and odor, 
among fruits and flowers and leaves and grasses 
and shrubs and trees. Great threads of unity 
obviously connect all the forms of terrestrial 
being, organic and inorganic ; but this we know, 
that, if only single specimens of all the plainly 



164 SIXTH LECTURE. 

separated species were attempted to be brought 
together into one Crystal Palace of a museum, we 
should have to roof in empires, instead of acres, 
in order to accommodate their mighty array: and as 
our eye would run over the whole superb collec- 
tion, and at last bring together the two termini — 
viz., the material man and the material stone 
just crumbling into dust — our sense would be 
that of a miraculous diversity efflorescing out of 
the unity of our world. So' with those other 
worlds that shine or hide in the vault above. 
They are all spheres, all have orbitual and prob- 
ably axial motions, all are governed by the same 
principle and law of gravitation, all are lighted 
and colored and warmed by the same mysterious 
element or impulse ; but on such basal unity is 
superimposed an almost infinite variety. Observe 
our solar system. One member of it is self-lu- 
minous, and, relatively to the other members, a 
nearly stationary body ; the others are dark, and 
far-wandering planets. One is one hundred miles 
in diameter, another nearly one hundred thou- 
sand, while still another contains more than 
eight hundred times as much matter as all the 
remainder of the system can boast. Some have 
atmospheres and seas, others have neither. Some 
have moons, others have none. Saturn rides 
forth in the porip of three great equatorial rings, 
as well as of eight moons ; no other planet is simi- 
larly furnished. These orbs of our system differ 



VARIETY IN VNITT. 165 

greatly in density — one is as lead, another as 
cork, another still i's mere vapor. One receives 
seven times as much light from the sun as 
we, another only a three hundred and sixtieth 
part e^f as much. Neptune's year is equal to 
one hundred and sixty-five of our years. Saturn's 
day is only one-half of our day. Of course 
the products and scenery of these worlds, as 
well as the constitution of their inhabitants, 
must differ exceedingly. But pass we on to 
the region of the fixed stars. Have we es- 
caped into immeasurable uniformity out of im- 
measurable variety ? Lo ! we skirt systems, clus- 
ters, firmaments, and never two alike, while some 
stand apart by whole universes of difference ! 
Lo, systems with several suns each, from one to a 
hundred ! Lo, systems lighted, some with white 
suns, some with ruby, some with emerald, and 
some with suns of many different colors ! Lo, 
suns differing exceedingly in size and amount of 
light they shed : for the great Sirius that flashes 
first magnitudes on all our charts as well as on 
the dazzled retina of the savage, is not as near 
to us as the little 61 Cygni, and its light must 
be equal to that of two hundred and fifty suns 
like our own ! Alcyone shines with a force 
of twelve thousand suns. And then we have 
suns themselves combined into systems of all 
sizes and shapes — systems of two, of three, 
of many, of millions, — firmaments which, un- 



166 SIXTH LECTURE. 

der the name of nebulae, arc .he last gen- 
eralization and most stupendous variety of mod- 
ern discovery : sometimes rolled up into spheres : 
sometimes gathered into circular or elliptic rings; 
now fan-shaped ; now like an hour-glass ; now 
broad wheels of compacted suns, large, glitter- 
ing, and sublime enough to under-roll the chariot 
of immeasurable God. There are not two leaves 
or grass-blades perfectly alike in all this verdant 
world ; not two worlds, nor systems of worlds, 
accurately alike in all the prodigious realms of 
astronomy. 

Now no one, to say the least, can claim that this 
vast variety imbosomed in unity makes positively 
against the idea of one Creator of boundless in- 
vention and executive faculty. On the contrary, 
it is just what we should have expected horn such 
a being. Given just such a many-sided, versatile, 
complete Deity as is affirmed — we should say 
that, in case he should set himself to produce a 
vast universe, he would be likely to produce one 
in which great outlines of unity would be steeped 
in immeasurable variation ; one in which resem- 
blance and diversity, both robed and featured like 
goddesses, would hold each other by the hand 
and go treading with wedded and festival step up 
and down the whole quickened area. Nay, this 
sort of universe one would make sure of finding ; 
would be greatly disappo'nted if he should not 
find. The eternal laws ol his own nature would 



VARIETY IN UNITY. 167 

demand it of the Great Builder. The invin- 
cible beauty and fitness of things would de- 
mand it. Perfect uniformity, however piled up 
in magnificent magnitudes — even a uniformity 
only varied after so cramped and frugal a fashion 
as would be perpetually suggesting poverty of re- 
sources — would belie the inexhaustible Divinity. 
If he build at all, he must not misrepresent and 
disparage himself in his work ; his fruitful na- 
ture, teeming with all imaginable fertilities and 
seeds, must surely blossom into very much that 
marvelous fruitfuluess of product and pattern 
which we observe. And when I am told of an 
author of nature whose being swarms in resistless 
force toward every point of the compass, nay of the 
sphere ; who is both a unit and a polygon, facing 
every desideratum and possibility with a flashing 
side, both of thought and action, that out-dazzles 
the sun — when I am told that such a being is 
the author of nature, and I then put myself 

\ forth under the open dome amid the glorious di- 
versities that root themselves in the glorious 
unity of nature, and open myself freely to all 
their subtle suggestions and magnetisms, I feel 
myself drinking in predispositions to faith, as the 

- exposed fleece drinks in the dew. I feel that 
again the doctrine matches facts, that again the 
theory has a comprehensive verisimilitude and pre- 
sumption, that Nature instead of saying that 
there is no God whore unity is arborescent 



108 SIXTH LECTURE. 

with endless varieties of beauty and power, sig- 
nificantly asks, **** Is there not such a Being? In 
fine, I feel that our continued lifting of the veil 
from the painting has disclosed a second trait 
strikingly characteristic of the Great Master to 
whom the work is attributed ; a trait which, added 
to the first, warrants our faith ward look in taking 
on new kindliness of aspect. 

Another characteristic of nature deserving of 
notice is the perfection of its details. 

The exquisite finish of nature in its minutest 
parts is about as wonderful as its vastness and va- 
riety. Scan that leaf. Examine the wing of that 
butterfly. Let the tinted and polished antennae 
of that moth glitter in the focus of your instru- 
ment. Subject to the skilfullest notice of science 
and art the smallest veins of any animal or vege- 
table. Push the analysis just as far as possible, 
and submit that last visible minimum of organi- 
zation in the crystalline lens of the cod, with its five 
millions of muscles and sixty thousand millions 
of teeth, to the most searching criticism of the su- 
perbest microscope. What exquisite details ! 
What elaborate refinement of workmanship ! It 
is not as with some master-piece of human paint- 
ing — the main points only cared for, while all 
the subordinate are too rude to bear close inspec- 
tion. Titian painted this landscape. Well, it is 
worthy of him — the general effect is beautiful. 
Yet, if you approach, and closely examine the fo- 



FINISH OF MINIMA. 169 

liage of the trees, the grass with which the can- 
vas is green, or even the limbs and features of 
the animals, they will be found very coarsely and 
incorrectly executed. The microscope turns the 
most finished work of man into coarseness and 
clumsiness — indeed, almost immediately carries 
the sight where traces of skill have totally disap- 
peared. Not so with the works of nature. A 
real landscape you may analyze to your heart's 
content, and inspect its details as critically as 
eye armored with lens can do, without finding 
the workmanship growing less exquisite the fur- 
ther you push inquiry. A real man — you may 
descend to the minutest particulars of his organi- 
zation, and get as near its primary elements as 
an Ehrenberg with his superb instruments and 
practiced vision can carry you, without finding 
the least falling off from that delicacy of execu- 
tion which appears on the larger masses and out- 
lines of the body. So everywhere among natural 
objects — the great and the small, the outlines 
and the minute filling-up, as far as utmost optical 
resources can carry our observation, are wrought 
with apparently the same overflowing outlay of 
attention and skill. It is not so in a few instances 
merely, nor in a thousand — it is so universally. 

That there are any so preposterous as to think 
that this feature of nature makes positively 
against the idea of a sparrow-watching, hair-num- 
bering, and thought-weighing God is, of course, 



170 SIXTH LECTURE. 

not to be imagined. Of course, it is a feature 
that fully harmonizes witli such an idea. A na- 
ture finished exquisitely down to the most infinites- 
imal of its details is just what one would have 
predicted from a God of this description. An- 
nounced the fact that He was about to create, 
and expectation would have stood on tiptoe to look 
for just such a nature as we see. A God for whose 
vision nothing is too small, who necessarily gives 
as complete attention to the affairs of an atom as 
to those of an empire, who can concentrate his 
almightiness with as much freedom and accuracy 
on a mathematical point as on a world, who is 
embarrassed no more by unlimited multiplicity 
than by unlimited minuteness of details, who can 
with equal ease paint a landscape on the point of 
a needle — say, if you please, forty thousand of 
such landscapes at once, with all their innumera- 
ble and minima particulars, back of the reticu- 
lated eyes of a single butterfly — can with equal 
ease do this, and roll a solar system on its tri- 
umphant path about the Pleiades ; do I not know 
that a being with such a striking attribute as this 
would surely give it expression in his works ? Do 
I not know that he who is equally at home in 
maxima and minima, and to whom beauties and 
glories in the world of infinitesimals would be just 
as apparent and practicable as they are in the 
world of infinites, would lay himself out on the 
one very much as on the other — would effulge 



WISDOM OF NATURE. 171 

himself into the microcosmos very much as into 
the cosmos ? When, then, I am told that such a 
being is the author of nature, and I proceed to 
place myself out under the open dome amid the 
exquisite elaborations that swarm on every hand 
down through the veriest miracles of littleness 
and detail, and to uncover myself candidly to all 
their subtle whisperings and magnetisms, I feel 
myself softly drinking in predispositions to faith, 
as the exposed fleece drinks in the dew, I so feel 
the force of a doctrine matching facts, and but- 
tressing itself again and again with comprehen- 
sive verisimilitudes and presumptions, that to 
me nature becomes articulate, and, instead of 
swearing with uplifted hand that there is no 
wondrous God, significantly points upward, and, 
with bated breath and expectant look, asks, " Is 
there not such a Being ? " — in fine, I feel that 
our continued lifting of the veil from the paint- 
ing has disclosed another characteristic of the 
Great Master to whom the work is attributed, the 
third of those several harmonies which, as suc- 
cessively presented, warrant us in looking faith- 
ward with ever-growing kindliness of aspect. 

Another feature of Nature is what I shall call 
its wisdom. 

The world is full of what, if accepted as the 
work of an intelligent being, would be called con- 
trivances — adaptations of means to ends — often 
of the most complex and elaborate description. 



172 SIXTH LECTURE. 

For example, the birds — how admirably adapted 
to flying ; in shape, feathers, bones, wings ! The 
fishes — how adapted to swimming and life in the 
water ; witness their shape, their smooth and 
unctuous scales, their pairs of fins, their tails and 
gills ! The land-animals — how adapted to walk- 
ing and running and feeding on the earth's sur- 
face ; to eat the grass or catch their special prey ! 
The trees — how adapted to stand firmly ; by their 
roots, their perpendicularity, their balanced 
branches, their moderate flexibility — how adapt- 
ed for shade, for abating the violence of winds, 
for fuel ! Or, if you will consider particular or- 
gans of the organic tribes, look at the bark of 
trees as related to their nourishment, at the web- 
foot in its double relation to land and water, at 
the teeth and other preparers of food for the 
stomach, at the stomach as a preparer of food for 
the blood, at the lungs as purifiers of the blood, 
at the heart as the engine for forcing the blood to 
all parts of the system, at the hand as the general 
servant of the whole body ; in short, at almost any 
organ of either animal or vegetable structures. 
The adaptations are wonderful. They are physi- 
cal miracles — the means are shaped and applied 
to the ends so exactly, beautifully, triumphantly. 
For example, no work of human ingenuity that 
ever you saw is equal to that natural marvel, the 
human eye — an organ having reference to an 
elemen* quite external to itself, whose chief source 



WISDOM OF NATURE. 173 

is millions of leagues distant ; and also to millions 
of external objects which compose our scenery of 
earth and sky — an organ placed in the most ele« 
vated part of the body so as to command the most 
extensive prospect ; placed in the front so as most 
readily to preside over the direction in which we 
habitually move ; placed in a strong bony socket 
which defends it from the heavier external in- 
juries; imbedded in a soft cushion, so that its del- 
icate texture can not be hurt by the bony walls 
around it, as it rests on them, and turns swiftly 
hither and thither at the bidding of the will ; 
furnished with lids, like curtains, to close over it 
in sleep, to wipe it, to cut off the outer rays of 
light that would confuse vision, to protect it by 
their involuntary and instantaneous shutting 
against the lighter kind of injuries ; furnished 
with an apparatus of muscles by which it can be 
rapidly turned at choice in any direction, so as to 
vary the field of vision as the needs of life may 
suggest ; furnished with a self-acting system of 
appliances by which the ball is kept lubricated for 
easy movement; furnished with a conduit to 
carry off the superfluous moisture ; furnished 
with just that shape, out often thousand possible 
shapes, which mathematicians have demonstrated 
to be the only one which can refract all the rays 
of light to a single surface, and thus afford dis- 
trict vision, viz., that of an ellipsoid of revolu- 
tion ; furnished with a retina or natural canvas 



174 SIXTH LECTURE. 

on which its pictures of external objects can be 
formed, of just the right size, and at just the right 
distance behind the lenses of the eye ; furnished 
with lenses of different substances having differ- 
ent refractive powers, thereby preventing the light 
from being resolved into the prismatic colors, and 
thus misrepresenting and uniforming objects ; fur- 
nished in front with a perforated membrane that 
by self-adjustment adapts it to different degrees 
of light, also with a system of pulleys and liga- 
ments that at a moment's warning alter its con- 
vexity and the relative position of parts so as 
to adapt it to objects at different distances and, 
what is more wonderful than all, provided in 
some inscrutable manner with the means of ex- 
pressing the mind itself, so that one may look into 
its crystal depths and see intellectuality and scorn 
and wrath and love, and almost every spiritual 
state and action. Now, if this is not an amazing 
congeries of adaptations, there is and can be noth- 
ing amazing. If found to be the work of a human 
artist, it would be called a perfect marvel of in- 
genuity and wisdom. And yet some insects have 
twenty thousand such eyes combined into one. 
But the eye is only one among an infinity of 
natural contrivances. Animate and inanimate 
nature is mountainous and glittering with them. 
Down into the regions of the infinitely small, 
whither only the most searching microscopes car- 
ry the sight ; up into the regions of the infinitely 



WISDOM OF NATURE. 175 

large and far, whither only mightiest telescopes 
lift our struggling knowledge ; among the mech- 
anisms of the atomic nations that people a sin- 
gle leaf, and among the mechanisms of those 
swarming celestial empires whose starry banners 
sweep our nightly skies — it is everywhere the 
same ; exquisite adaptations crowding exquisite 
adaptations, profound contrivances (so inven- 
tors and mechanicians would be tempted to call 
them) heaped on profound contrivances, in such 
endless amounts and varieties of wise structure, 
as exhausts all human understanding and dwarfs 
into nothingness all the products of human in- 
genuity. 

Does such a nature as this swear against a 
Divine Contriver. Does it protest against him, or 
testify against him, or breathe even a suspicion 
against him ? Many absurd things are done in the 
world : but it will be hard to find the man who will 
care to deny the positive and emphatic harmony 
between the doctrine of an omniscient and omnip- 
otent God and a universe crowded with such 
splendors of natural mechanics. A God of end- 
less invention, and whose powerful and skilled 
hands can magnificently realize all that he has 
magnificently planned — we should expect that 
such a being, in case he should create a nature, 
would set it all ablaze with the monuments of 
his supreme intelligence and power — should be 
disappointed to find no such monuments, but, in 



176 SIXTH LECTURE. 

their stead, mere stupidity or tameness of work. 
We should call the work unworthy of the work- 
man. Nay, we should hasten to say to ourselves 
that we must have mistaken him — He could 
really be nothing more than such a petty divinity 
as the poor heathen have fabled to themselves. 
For we should be sure that one having unlimited 
command of ways and means, both as a knower 
and worker, would display it in his works. It 
being just as easy for him to have exquisite 
adaptations, and a gloriously endless variety of 
them, as to have no adaptations at all — it is 
plain what sort of nature he ought to make and 
would make. Now let me be told of a framer of 
nature in whom are hid all the treasures of wis- 
dom and knowledge, whose light lias in it no dark- 
ness at all, whose smallest deeds have from the 
hoary everlasting been pavilioned and charioted 
toward being amid the glories of Almighty Om- 
niscience ; and I then place myself out under 
.the open dome mid the wilderness of wonderful 
constructions and chemistries, and candidly un- 
cover myself to all their subtle sympathies and 
magnetisms — I feel myself, all silently, drinking 
in predispositions to faith, as the exposed fleece 
drinks in the dew. I feel that the God who is af- 
firmed is just the God to match the nature which 
I see — here the ball and there the socket, here 
the foot Titanic and there its footprint, here the 
shapely hand and there its glove, here the sover- 



POWER OF NATURE. 177 

eign sword and there the golden scabbard that just 
fits it — that these poble adaptations and mechan- 
isms, spangling and blazoning all the fields of 
matter, arc in rejoicing sympathy with the idea 
of a Creator who is wonderful in counsel and ex- 
cellent in working ; that the alabaster-box of 
precious wisdom that has been emptied, not only 
on the queenly head and shining tresses of Na- 
ture but on her very feet, scents bravely of One 
who is himself a " mountain of such spikenard ;" 
that, in fact, the theory is again smiled upon 
by a comprehensive verisimilitude and presump- 
tion ; that Nature, instead of swearing with 
uplifted hand that there is no All-wise Creator, 
with flushed cheek and upward-glancing eye of 
expectation, significantly asks, " Is there not such 
a Being ? " In fine, I feel that our continued 
lifting of the veil from the painting has disclosed 
still another characteristic of the Great Master 
to whom the work is attributed ; has cleared up 
another stretch of that vista at the end of which 
is Titian at his easel — the fourth of those several 
harmonies, which, as successively presented, war- 
rant us in looking faithward with ever-growing 
kindliness of aspect. 

Another striking feature of Nature is its power. 

No contemptible degree of force resides in the 

muscles of some men. — the Samsons and Milos 

of their time. Huge rocks are lifted, tough oaks 

are riven, great structures are shaken down by 

12 



178 SIXTH LECTURE. 

their hands. Many brute animals display still 
greater muscular strength ; witness the elephant, 
and those gigantic mammals which towered 
and ruled over the post-tertiary savannas. A 
combination of animal forces with what are called 
the mechanical powers often generates measures 
of force more striking still ; and when men stand 
by such piles as the Egyptian pyramids, they are 
deeply impressed with the prodigious uplift that 
must have put those mighty blocks in their high 
places. But it is to inanimate nature that we 
must go for our most brilliant examples of phys- 
ical force. What power hi the wind, when, as a 
tornado, it sweeps along at more than one hun- 
dred miles an hour ; demolishing mansions, up- 
rooting forests, and lifting ponderous ships far in- 
land on their eddies ! What power in the ocean- 
swell as it tosses an entire navy to the skies with 
apparently as much ease as if it were a single 
cockle-shell ! — What is this that comes rushing 
through the landscape with smoky breath and 
thunderous step, dragging thousands of tons at 
the pace of winds ? Within that flying iron cra- 
ter is imprisoned one of nature's brawniest forces, 
steam — throwing off feats of toil with its vaporous 
arms, which arms of flesh and blood have never 
even been fabled to do. — What have we here ? A 
few barrels filled with very simple black grains. 
One has but to drop a spark among them to wit- 
ness a sudden development of power that shall 



POWER OF NATURE. 179 

deafen earth and heaven with its voice, and lift a 
city into mid-air. -7- Would yon see a mightier 
energy still ? It is the year 1755. An unwonted 
trembling stirs the air and ground of Lisbon. In 
a few moments the broad city is in heaps. The 
plain around runs in waves, like the sea when 
lashed by a tempest. See — the distant moun- 
tain-ranges themselves impetuously shake and 
rend and topple ; Europe, to the Highlands of 
Scotland, heaves ; heaves Africa ; heaves the 
whole broad Atlantic, with all its huge gravi- 
ties, from the Pillars of Hercules to the New 
World ! When oceans and continents are so 
tossed and shot aloft, what stalwart shoulders of 
gas and steam and fire are heaving at the mighty 
burden ! Other forces among us are not small ; but 
this of the earthquake is easy king over all these 
terrestrial children of pride. Terrestrial, I say : 
but there are forces not terrestrial which are of a 
still linger and loftier pattern — celestial forces, 
to which those of our earth are what the bubble- 
globules of the children are to the globed worlds 
of space. When such a planet as Jupiter is 
moving at the rate of some thirty thousand miles 
an hour ; when such a sun as ours is moving at 
the rate of some three thousand miles a minute ; 
when such a nebula as our Milky Way, with its 
eighteen millions of suns, goes wheeling at the 
same average speed about its center of gravity 
— there is a momentum for you, a magazine 



180 SIXTH LECTURE. 

of force by the side of which earthquakes are 
puny, and all the stormy winds that ever blus- 
tered and fought in their fabled caves mere zeros ! 
Some say that there is but one force in all nature 
— none perhaps more apt to say it than the 
rejecters of the supernatural — that the forces 
which pump and assimilate and reject in every 
blade of grass and leaf and animal fiber; the 
forces that throb in every ray of light and heat 
and electricity and magnetism, the forces that 
swell and toil in every atom of matter, the me- 
chanical forces, the chemical forces, the spiritual 
forces, the forces here and the forces yonder to 
the universe's last suburb — that all these forces, 
with their incomprehensible sum-total Of simul- 
taneous impulses, are, after all, but branches of 
one great central force pushing outward in an in- 
finite variety of directions and forms. If this is 
so — and who is competent to positively deny it — 
what a single force that is which can diffuse itself 
over so immense an area, and divide itself so in- 
finitely, and yet thunder away at special points 
with such marvelous and terrible energy ! If 
this is not so, still what a wondrous hive of 
swarming and independent dynamics in this wide 
uature of ours ! 

Of course, no one could have the hardihood to 
say that a nature stocked with such energies as 
these makes positively against the doctrine of a 
Creator who is himself an Almighty Force. On 



POWER OF NATURE. 18.1 

the contrary, there is a friendly harmony between 
the doctrine and the fact. Were we to find in 
actual existence a Personal Power to whom noth- 
ing is impossible, and learn that he is about to 
produce a universe, we should expect to see pro- 
duced just such a wonderfully strong nature as we 
actually have — a nature peopled with strengths, 
momenta, brawny agencies of most imposing forms 
and magnitudes. A weak system, a system that 
is puny in its operations and trifling in its effects, 
would misrepresent him — shall I not say, would 
be unworthy of him ? Most persons would cer- 
tainly call it unsuitable ; would say that his 
very nature as an Infinite Power would demand 
of him that he should produce a system that 
would be continually turning out the greatest re- 
sults, and so must include forces of the greatest 
efficiency. When, then, I am told that a Sublime 
Force, who has Almighty for his name, is the au- 
thor of nature ; and I then proceed to place my- 
self out under the open dome amid the pulsings 
and tossings of innumerable and sometimes im- 
measurable momenta, and so lay myself honestly 
open to all their subtle hints and magnetisms; I 
feel myself silently drinking in predispositions to 
faith as the exposed fleece drinks in the dew — I 
feel that the doctrine matches facts ; that the as- 
serted creator and creation fit each other as do 
the die and the face of the coin which it has 
6tamped ; that the theory has at least the bene- 



182 SIXTH LECTURE. 

diction of yet another verisimilitude and presump- 
tion ; that Nature, instead of making oath with se- 
rene brow and uplifted hand, that there is no won- 
drous God, significantly asks, with abashed voice, 
" Is there not such a Being?" — in fine, I feel 
that, as the veil continues to rise from the face of 
the painting, it reveals still another characteristic 
of the Great Master, clears up another stretch of 
that vista which conducts the sight toward Titian 
bending over his canvas — the fifth of those sever- 
al harmonies which, as successively presented, 
warrant us in looking faith ward with ever-grow- 
ing kindliness of aspect. 

Another feature of Nature is its remarkable re- 
lation to law. 

Notice law and its exceptions — the general 
steadfastness of modes of being and action in na- 
ture, and the occasional breaches in that stead- 
fastness. 

On the earth's surface, in its dark interior, in 
the air and vault above, in the instant present and 
the ancient past — everywhere, law waves its 
mighty scepter. Atoms and masses, the ponder- 
ables and inponderables, the organic and inor- 
ganic, the living and dead — all are evidently 
subjected in their modes of being and action to 
certain fixed rules, sometimes particular, but 
more often covering whole classes of objects. 
Not a particle floats at random or as a unit : not 
a leaf grows or falls save according to rigid gene- 



RELATION TO LAW. 183 

ral principles of science. All chemical elements 
have their modes- and measures of combination to 
which they steadfastly adhere. All heat, electri- 
city, magnetism, gravity, act according to abiding 
methods which philosophers have gradually dis- 
covered and arranged into the sciences of natural 
philosophy. The great processes of vegetable and 
animal life proceed after the same forms and steps, 
from age to age. The stone beds of the world are 
formed and modified in certain set ways which 
are the same now as in the periods anterior to 
man. Even the weather, so often called fickle, 
has its stable methods ; almost every year bring- 
ing to light some new general fact in meteorology, 
or extending the application of an old one. Day 
and night succeed each other, every twenty-four 
hours, without variation. The seasons do not 
change their order or general character. All of 
Kepler's and Newton's laws are as operative to- 
day as they ever have been since their discovery. 
The planets shoot round the sun and are circled 
by their own moons, on substantially the same 
elliptical orbits, in the same times, and with the 
same principles of alternate retardation and accel- 
eration as of old. All known changes in the plan- 
etary orbits have been found to be bound in a 
law of periodicity which is apparently invariable. 
So beyond the solar system. Law still ; nothing 
but law ; law everywhere on ten thousand bla- 
zing thrones ; largely the same laws that prevail 



184 SIXTH LECTURE. 

in our own system ! As far as we can observe — 
and it is no little that has been observed — those 
distant orbs reverence the various principles of 
gravitation and mechanics, and keep as rigidly to 
their behests, as when the earliest astronomy gazed 
at them from its rude Uraniberg of a hill-top. 
And every man of science is well persuaded that, 
could his observation alight on particular orbs of 
those remote and twinkling hosts, he would find 
their minutest details bound up in the chains of 
the same adamantine regularity that rules our 
own globe. 

So in general we speak. But we must not be 
understood to speak with absolute precision of 
language. In this wide scene of steadfast ar- 
rangements, there are outbreaks of anomaly — 
ruptures and rents and dislocations in the habits 
and ongoings of nature, like those in the strata 
of the earth. It is a settled law of nature that 
like shall produce like ; yet from perfect animals 
and vegetables occur occasional monstrosities of 
organization. It is a settled course of nature 
that certain substances, called poisons, if freely 
introduced into animal systems, destroy life ; yet 
now and then a man is found who is even nour- 
ished by these agents of destruction. It is a fixed 
mode of nature that frost withers flat foliage ; yet 
the flat leaves of the wild laurel flourish out our 
hardest winters. It is a fixed way of nature that 
the heavenly bodies move in ellipses ; yet there 



RELATION TO LAW. 185 

is reason to believe that some comets have been 
found moving on the curve called a parabola. 
The steadfast habit of nature is against a general 
planetary deluge, or conflagration, or glacier- 
period, or destructive convulsion ; yet such disas- 
ters, if geology may be trusted, have several times 
occurred, at immense intervals, in the history of 
our own planet. Great exceptional events ; 
phenomena without fellows through an astonish- 
ing stretch of ages ; what have the appearance 
of broad fractures and dislocations of nature, 
though in reality they may be the rare resultants 
and accumulations of innumerable natural forces 
and laws crossing each other in all directions ; 
the entire destruction and rehabilitation of animal 
and vegetable species — such events have taken 
place on this globe again and again. Repeatedly 
has the earth been drowned and torn in pieces. 
It has been piled with snow and ice from pole to 
pole. It has been all ablaze and fused. And is 
it not on the idea of such a conflagration that we 
can best account for the new stars that have some- 
times flashed suddenly on the sight with all the 
splendor of Venus at its brightest, and, after a 
few months of changing color and gradual decay, 
finally disappeared ? Thus in the bosom of a 
general steadfastness are found occasional out- 
breaks of anomaly. It is as among the geologic 
strata — where are found faults, dislocations, fis- 
sures, and even reversions of those great rock- 



186 SIXTH LECTURE. 

beds which in general are laid down on a plan of 
utmost regularity. The course of nature is like 
some great thoroughfare, which advances through 
great distances without the slightest solution of 
its continuity, but at last finds a great river thrust 
squarely across its track. On this side the thor- 
oughfare, on that side the thoroughfare, and here 
the broad, deep flow of the bridgeless river — 
a river worth to the public, it may be, many 
times what the perfect continuity of the road 
would be. 

Xow this mucli is certain. Xo one can say that 
this characteristic of nature makes positively 
against such a steadfast and yet miracle-working 
God as is affirmed in the Christian Scriptures. 
Instead of opposition, there is positive harmony 
between the fact and the doctrine. Indeed, such 
a nature as is observed is just what one would 
have expected to come from such a Creator as is 
taught. Nay, as general laws are necessary to 
make science possible, to enable men to forecast 
and profit by experience, to serve as a basis for all 
comprehensive business and for all civil govern- 
ment — as the broader and profounder the intel- 
ligence, the more it is pleased witli and tends to 
work by general principles, we may say that the 
very nature and circumstances of Deity would de- 
mand of him, in case he should create, to create a 
generally steadfast, law-abiding universe. At the 
same time, a miracle-worker — one who sees acer- 



RELATION TO LAW. 187 

tain essential imperfection and intractability in 
seco id causes, preventing their matching on all 
occasions the perfection of his ideas ; who, more- 
over, sees it undesirable to allow mere nature to 
hide its Maker altogether behind its swarming 
screen, and give to the ideas of necessity and fatal- 
ity full sweep in human minds — I say, such a 
being would be under a loud call to provide in the 
constitution and course of nature such sugges- 
tions and prophecies of miracles as would gradu- 
ally, though perhaps unconsciously to them, pre- 
pare the minds of men for those crowning 
abnormals of the system. He must have the 
glory of his personal agency glimmer through 
occasional rents in the uniformity of nature. 
An anomaly-sprinkled, miracle-suggesting, as well 
as stable, universe must proceed from his won- 
drous hand. He would be in conflict with 
himself were he to produce any other. And 
when I am told of one who is actually just 
this sort of divinity — both law and miracle : 
both giver and keeper to an almost infinite 
extent of moral laws which shall not pass away ; 
while his iron will, throned as supremely in 
the realm of matter as of morals, yet launches 
forth into special providences and miracles on 
extraordinary occasions — when I am told of 
him, and I then place myself out under the 
open dome amid the massive but occasionally 
rifted uniformities, and open myself freely to all 



188 SIXTH LECTURE. 

their subtle hints and magnetisms. I feel myself 
softly drinking in predispositions to faith, as the 
exposed fleece drinks in the dew. I feel that the 
doctrine and the facts are at one : that the asserted 
Creator and the observed creation fit each other 
as do the signet and the seal just stamped ; that 
another verisimilitude spreads blessing, if trem- 
ulous, hand over the theory ; that Xature in- 
stead of sonorously swearing that there is no 
Divine Being whose double name is Law and Mira- 
cle, significantly asks, with abashed and startled 
tones. •• Is there not such a Being ? " In fine, I 
feel that, as the veil continues to rise from the face 
of the painting, it reveals still another character- 
istic of the Great Master, clears up another stretch 
of that vista which conducts the sight toward 
Titian bending over his canvas — the sixth of 
those several harmonies which, as successively pre- 
sented, warrant us in looking faithward with ever- 
growing kindliness of aspect. 

Another feature of Xature is its wonderful re- 
lation to time and motion. 

How long has our race existed ? The infidel 
may choose to say a hundred thousand years ; 
none will say less than six thousand. How long 
has the earth itself existed ? The atheist may 
choose to say. Forever. The geologist, thinking 
of his coal beds and deltas and rocky strata sown 
with the bones of extinct species, and of the time 
requisite for their formation, is sure of several 



RELATION TO TIME AND MOTION. 189 

hundred thousand years. How long are the 
earth and its confederates in the solar system 
calculated to endure ? Geometry declares that 
no element of decay within endangers the sta- 
bility of the system of the world. That year 
which circumscribes our seasons is only three 
hundred and sixty-five days ; but the earth has 
another year to which this is a mere point — its 
pole goes nodding through space in a circle which 
it takes twenty-five thousand years to traverse. 
What think you of a planet whose winter is more 
than forty of our years, of a comet whose year is 
more than thirty of our centuries, of a sun whose 
year is more than eighteen thousand of our mil- 
lenniums? All the planetary orbits pass through 
cycles of changes varying in length from a few 
centuries to nine thousand, to seventy thousand, 
to even many million years ; but the greatest of 
these planetary cycles are as nothing compared 
witli those enormous periods which bound the 
perturbations and express the secular equations 
of the sun and fixed stars — periods including 
more years than imagination has ever succeeded 
in realizing to itself. What amazing longevities ! 
What portentous numerals! They are hiero- 
glyphics of the everlasting. They lift us among 
the dizziest peaks of the sublime. 

These immense periods, interspersed with others 
exceedingly small, sometimes express an exceed- 
ingly slow movement among the powers of nature. 



190 SIXTn LECTURE. 

In other cases, the movement with which they 
are connected is exceedingly rapid. The times 
consumed in the formation of the coal-beds and 
rock-strata, and in the long perturbations of the 
planetary and stellar orbits, are examples of the 
first class of periods ; the years of the planets and 
stars in their orbits are examples of the second. 
In the first class, natural forces creep along to 
their objects with miraculous slowness ; in the 
other, they flash along with swiftness equally 
astounding. Some orbits gradually lengthen 
themselves, say an inch in a thousand years. 
Some of the stars dart along their year of one 
hundred and eighty thousand centuries at the in- 
comprehensible rate of one hundred and eighty 
thousand miles an hour. Could we plant our- 
selves immovably at a certain point in the celes- 
tial spaces, and see our sun go sailing by with all 
its glorious squadrons of planets and moons — 
sailing down the abyss as if driven by ten thou- 
sand hurricanes — would not the sight of such 
celerity almost irrecoverably daze both senses and 
spirit ? 

If, now, one should start up to say that these 
great cycles, imbosoming unutterable extremes 
of movement, makes positively against an Eter- 
nal God who is able to move to his purpose like 
the light or at a rate so trifling as to be quite im- 
perceptible by human senses, we should laugh his 
logic to scorn. We know better. These are facts 



RELATION TO TIME AND MOTION. 191 

that palpably agree with such a theism. Instead 
of contradicting it, they express a state of things 
that might have been expected from a being who 
has both unlimited time and unlimited speed at 
his disposal — who, if he chooses to wait, has 
never occasion to haste ; or, if he chooses to haste, 
has never occasion to wait — who is alike able to 
dart on his purpose as if infinite whirlwinds were in 
his wings, or to approach it at a rate so minute that 
no human sense can discern the movement in the 
lapse of generations. Suppose such a God to be 
about to create a nature, could you not confidently 
predict after this manner — " This Being of mighty 
periods will establish mighty periods : this Being 
who can readily proceed on his endlessly varied de- 
signs, at all imaginable and unimaginable rates of 
speed, will diversify his works with all the veloci- 
ties." A God who himself has no duration to speak 
of — if there may be such a God — would never 
have stored his nature with such mighty cycles ; a 
God who himself never did a swift thing would 
never have set his laws to spurring on planets and 
suns so astoundingly ; a God who himself never 
did a slow thing would never have yoked such 
slow-footed forces to events, as we observe actually 
dragging at some of them. It is only a God who 
has substantial forevers on his hands, and who on 
occasion can lighten and on occasion can linger 
ineffably along the highway of his purposes, who 
is properly represented by such a nature. In case 



192 SIXTH LECTURE. 

lie gives any nature at all, his character demands 
of him to give just this — one expressing his own 
attributes. So when I am told of one whose lon- 
gevity is eternity, whose orbit of existence has an 
infinite axis, who reaches an Atonement after 
slowly beating toward it for forty centuries, who 
is ages and dispensations in establishing his king- 
dom in the world, who commonly approaches the 
punishment of sinners with steps lingering through 
numberless delays and forbearances, and who yet 
sometimes yokes steeds of wind and fire and foam 
to his car — as when some Korah and his com- 
pany go down quick into the pit ; or some Uzziah, 
profanely grasping an ark, falls dead ; or some 
Ananias and Sapphira, lying to the Holy Ghost, are 
rushed to judgment in an instant's brief space — 
when I am told of such a God creating nature ; 
and I then betake myself abroad under the open 
^dome amid those swarming and wondrous orbits 
of time, now scarred and smoking with the hot 
hoofs of electric forces, and now pressed by the 
velvety and trackless feet of forces born of the 
snail ; and frankly lay myself open to all their 
subtle hints and magnetisms — I feel myself silent- 
ly drinking in faith, as the exposed fleece drinks 
in the dew — I feel that there is a significant 
matching of what we are taught with what we 
observe ; that such theism is on most excellent and 
embracing terms with Nature, which, so far from 
saying with uplifted, oath-making hand, ' that 



MYSTERIOUSNESS OF NATURE. 193 

there is no Eternal God who, as an agent, is equally 
at home in an instant and an age,' at least stands 
tremulously querying, " Is there not such a Be- 
ing ? " — in fine, I feel that, as the veil continues to 
rise from the face of the painting, it reveals still 
another characteristic of the Great Master, clears 
up another stretch of that vista which conducts 
the sight on Titian painting away suhlimely at his 
glowing and glorified landscape — the seventh of 
those several harmonics which, as successively 
presented, warrant us in looking faithward with 
ever-growing kindliness of aspect. 

Another feature — the mysteriousness of Na- 
ture. 

Who does not know it? — terrestrial nature 
is one huge sphinx. She vomits enigmas on us 
in seas. Riddles too profound for the highest 
science yet in our possession lurk in every ray 
of light, in every blade of grass, in every rudest 
stone. Only some of the coarser facts in rela- 
tian to a few things here and there, have been 
picked up and systematized; and these are what 
compose our boasted sciences. From surface to 
center, the earth is choked with mysteries whose 
stony rind lias never yet received a blow, much 
less a fracture, from the mallet of investigation. 
Come now, ye great Computers, compute for us 
how long it will be before the science, which loses 
itself at the very threshold of the complexities 
of this world, will be able to swoop down with 

13 



194 SIXTH LECT\ BE. 

triumphant wing upon the surfaces and to the 
fiery centers of those fellow planets that myste- 
riously weave and interweave paths across the 
concave, and thoroughly solve the prohlem of all 
their swarming contents ! A disorderly maze 
are the apparent paths of the members of our 
solar system ! But you say that the real paths 
are not as intricate as the apparent. Take your 
stand, then, at the sun, and observe planets and 
comets going and coming at all distances and 
rates of velocity and directions ; while around 
most of the larger planets are similarly moving, 
other systems of satellites — is it not an intricate 
as well as a brave sight ? Can you see through 
the mazy plan ? But you say that it has been 
seen through, and planetariums have been made 
that clearly represent the whole thing to us with- 
in a few feet of space. How many centuries 
and philosophers, Copernicus — Copernicus, I 
say, away yonder in the depths of four hundred 
years ago — did it take to make that orrery and 
solve that riddle of the system of the world ? 
Indeed, it is yet very far from solution. Astron- 
omers can only completely account for the move- 
ments of a system of two bodies. A system of 
three is quite beyond them ; one of a hundred 
and more bodies, like our solar system, immeasur- 
ably beyond them. There is not even a hope 
that science, with all its dynamical calculuses, 
will eve/ overtake this higher problem. But 



MTSTERIOUSNESS OF NATURE. 195 

there is a higher problem still. Solar system 
revolves around solar system; a group of such 
systems around a similar group ; a cluster of 
such groups around a similar cluster ; a firma- 
ment of such clusters around a similar firmament. 
Indeed, as we have seen, the whole universe of 
stars, with all the countless fleets of planets and 
moons which they represent, must, according to 
the law of gravity, revolve about a last center of 
centers. Let us go to it. Standing at this 
Heaven — for is not this the dazzling metropolis 
where dwells the sublime Cesar of the creation — 
standing at this wondrous point, and looking 
forth on the countless nebulae coming and going 
at all imaginable distances, speeds, and direc- 
tions — lo, what a glorious scene of bewilder- 
ment and unsearchable complexity ! It fairly 
takes away our breath to look. There is no 
more spirit left in us. If a system of three 
bodies is too much for the most subtle and com- 
prehensive science yet known, what can ever be 
done by all coming generations and geniuses, 
however imperial, toward mastering such laby- 
rinthian immensity of involved orbs ? 

Now hearken to the Christian Scriptures — 
affirming a Maker of nature who is himself the 
mightiest of all enigmas. " Verily, thou art a 
God that hidest thyself — Canst thou by searching 
find out God ; canst thou find out the Almighty 
to perfection — It is high as heaven ; what canst 



196 SIXTH LECTURE. 

thou do : deep as hell ; what canst thou know ? " 
Does the aspect of nature contradict this doc- 
trine ? Who will presume to deny that the in- 
comprehensible materialism about us, to say 
nothing of the more incomprehensible spiritual- 
ism within us, is just what one would expect to 
find issuing from the hands of an incomprehensi- 
ble Creator — a being mysteriously without a. 
beginning, mysteriously self-existent, mysteriously 
able to make the greatest and noblest things out 
of nothing by simple volition, mysteriously all- 
knowing, mysteriously unfettered in. the appli- 
cation of his power and knowledge by all con- 
ditions of space and duration and personal 
presence, mysteriously Three in One — in short, 
a being enveloped in a terrible pomp and majesty 
of sunset-clouds, whose broken lines never per- 
mit the orb that glorifies them to appear, even 
for a moment, in clear and golden contour on 
our rapt sight. Such a being, setting out to 
create, would be likely to give us the present 
enigmatic universe, nay — for why state the mat- 
ter so feebly — would be sure to give it. Like, 
every other copious author, he would reproduce: 
his own traits. An unutterable sphinx himself, 
his creatures would be sphinxes. A nature from 
the hands of God that I can comprehend, or 
make any approach to comprehending — prepos- 
terous ! A creation that to me, with my low 
place and filmy vision and narrow -orbit, is not 



MTSTEIilOUSNESS OF NATURE. 197 

steeped in seas of mystery — preposterous ! If a 
Jehovah build the temple of nature at all, he will 
found it on mysteries, frame it with mysteries, 
cover and dome it with mysteries, pillar and 
ballast it with mysteries, pave and ceil it with 
a mosaic of mysteries — surely he will. And 
when I am told of a being whose own nature is 
an overwhelming problem ; whose attributes have 
no horizon, no zenith, and no nadir; whose ends 
respect all possible objects and interests, and 
spread themselves out in plans of boundless \ast- 
ness whose merest corners and differentials only 
are visible to men of the widest scope : when I 
am told of him, and I then place myself out un- 
der nature's open dome, amid its Protean inscru- 
tableness of leaf and star, of whole crowded earth 
and circumventing heavens — the peopled heavens 
where sweep in inextricable maze the hurricane 
hosts of advancing and retreating orbs ; and open 
my soul candidly to all their silent suggestions 
and magnetisms — I feel myself drinking in faith, 
as the fleece spread out under the stars drinks in 
the dew — I feel that the facts give embracing 
arms to the doctrine ; that the actual universe, 
instead of swearing with decisive voice and hand 
uplift to heaven that there is no inscrutable God, 
significantly asks with panting whisper aud color 
that comes and goes, " Is there not such a Being ? " 
In fine, I feel that our continued lifting of the 
veil from the painting has disclosed another char- 






6 



198 SIXTH LECTURE. 

acteristic of the great master to whom the work 
is attributed ; has cleared up another stretch of 
that vista which conducts the sight to Titian in 
the act of glorifying his canvas into the Milanese 
Coronation-Christ — another of those many har- 
monies which, as successively presented, warrant 
us in looking faith ward with ever-growing kindli- 
ness of aspect 



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